It is a generally accepted standard that editors should attempt to follow, though it is best treated with common sense, and occasional exceptions may apply. Any substantive edit to this page should reflect consensus. When in doubt, discuss first on the talk page.
This page guides the presentation of numbers, dates, times, measurements, currencies, coordinates, and similar items in articles. The aim is to promote clarity, cohesion, and consistency, and to make the encyclopedia easier and more intuitive to use.
Where this manual gives options, maintain consistency within an article unless there is a good reason to do otherwise. The Arbitration Committee has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style; revert-warring over optional styles is unacceptable.[a] If discussion fails to resolve the question of which style to use in an article, defer to the style used by the first major contributor.
Quotations, titles of books and articles, and similar "imported" text should be faithfully reproduced, even if they use formats or units inconsistent with these guidelines or with other formats in the same article. If necessary, clarify via [bracketed interpolation], article text, or footnotes.
Except on pages that are inherently time-sensitive and updated regularly (e.g. the "Current events" portal), terms such as now, currently, to date, so far, soon, upcoming, ongoing, and recently should usually be avoided in favor of phrases such as during the 2010s, since 2010, and in August 2020.[note 1] For current and future events, use phrases such as as of September 2022 or since the beginning of 2022 to signal the time-dependence of the information; use the template ((as of)) in conjunction.
Dates, years, and other chronological items should be linked only when they are relevant to the subject and likely to be useful to a reader; this rule does not apply to articles that are explicitly on a chronological item, e.g. 2002, 19th century(as discussed at Wikipedia:Linking § Chronological items).[d]
Dates in article body text should all use the same format: She fell ill on 25 June 2005 and died on 28 June, not She fell ill on 25 June 2005 and died on June 28.
Publication dates in an article's citations should all use the same format, which may be:
the format used in the article body text,
an abbreviated format from the "Acceptable date formats" table, provided the day and month elements are in the same order as in dates in the article body, or
the format expected in the citation style being used (but all-numeric date formats other than yyyy-mm-dd must still be avoided).
For example, publication dates within a single article might be in one, but only one, of these formats (among others):
Jones, J. (20 September 2008)
Jones, J. (September 20, 2008)
Access and archive dates in an article's citations should all use the same format, which may be:
the format used for publication dates in the article (see above);
the format expected in the citation style adopted in the article; or
For example, access/archive dates within a single article might be in one, but only one, of these formats (among others):
Jones, J. (September 20, 2008)... Retrieved February 5, 2009.
Jones, J. (20 Sep 2008)... Retrieved 5 Feb 2009.
Jones, J. (20 September 2008)... Retrieved 2009-02-05.
When a citation style does not expect differing date formats, it is permissible to normalize publication dates to the article body text date format, and/or access/archive dates to either, with date consistency being preferred.
Articles on topics with strong ties to a particular English-speaking country should generally use the date format most commonly used in that nation. For the United States this is (for example) July 4, 1976; for most other English-speaking countries it is 4 July 1976.
Articles related to Canada may use either format with (as always) consistency within each article. (see Retaining existing format)
In topics where a date format that differs from the usual national one is in customary usage, that format should be used for related articles: for example, articles on the modern US military, including biographical articles related to the modern US military, should use day-before-month, in accordance with US military usage.
If an article has evolved using predominantly one date format, this format should be used throughout the article, unless there are reasons for changing it based on strong national ties to the topic or consensus on the article's talk page.
The date format chosen in the first major contribution in the early stages of an article (i.e., the first non-stub version) should continue to be used, unless there is reason to change it based on strong national ties to the topic or consensus on the article's talk page.
Where an article has shown no clear sign of which format is used, the first person to insert a date is equivalent to "the first major contributor".
Use either the BC–AD or the BCE–CE notation consistently within the same article. Exception: do not change direct quotations, titles, etc.
An article's established era style should not be changed without reasons specific to its content; seek consensus on the talk page first (applying Wikipedia:Manual of Style § Retaining existing styles) by opening a discussion under a heading using the word era, and briefly stating why the style should be changed.
BCE and CE or BC and AD are written in upper case, unspaced, without a full stop (period), and separated from the numeric year by a space (5BC, not 5BC). It is advisable to use a non-breaking space.
AD appears before or after a year (AD106, 106AD); the other abbreviations appear only after (106CE, 3700BCE, 3700BC).
In general, omit CE or AD, unless to avoid ambiguity or awkwardness
Typically, write The Norman Conquest took place in 1066 not 1066CE nor AD1066
But Plotinus lived at the end of the 3rd century AD (not simply at the end of the 3rd century) may avoid confusion unless the era is clear from context.
One- and two-digit years may look more natural with an era marker (born in 2AD or born January 15, 22CE, not born in 2 nor January 15, 22).
Ranges beginning in BC/BCE should specify the ending era: write 450 to 200 BCE or 450 BC to 200 BC or 450 BCE to 200 CE, but not 450 BCE to 200. (see Ranges)
Uncalibrated (BCE) radiocarbon dates:Calibrated and uncalibrated dates can diverge widely, and some sources distinguish the two only via BCE or BC (for calibrated dates) versus bce or bc (uncalibrated). When feasible, avoid uncalibrated dates except in direct quotations, and even then ideally give the calibrated date in a footnote or square-bracketed note – [3250 BCE calibrated], or at least indicate the date type – [uncalibrated]. This also applies to other dating systems in which a calibration distinction in drawn.
BP or YBP: In scientific and academic contexts, BP (Before Present) or YBP (years Before Present) are often used. (Present in this context by convention refers to January1, 1950.) Write 3000 yearsBP or 3000YBP or 3000years before present but not forms such as 3000 before present and 3000 years before the present. If one of the abbreviated forms is used, link to Before Present on first use: The Jones artifact was dated to 4000YBP, the Smith artifact to 5000 YBP.
Other era systems may be appropriate in an article. In such cases, dates should be followed by a conversion to Anno Domini or Common Era, and the first instance linked: Qasr-al-Khalifa was built in 221AH (836CE), or in 836AD (221AH).
Astronomical year numbering is similar to the Common Era. There is no need to follow a year expressed with astronomical year numbering with a conversion to Common Era. The first instance of a non-positive year should still be linked: The March equinox passed into Pisces in year−67. (The expressions −67 and 68 BCE refer to the same year.)
A date can be given in any appropriate calendar, as long as it is (at the minimum) given in the Julian calendar or the Gregorian calendar or both, as described below. For example, an article on the early history of Islam may give dates in both Islamic and Julian calendars. Where a calendar other than the Julian or Gregorian is used, the article must make this clear.
Current events are dated using the Gregorian calendar.
Where it's not obvious that a given date should be given in Julian alone or in Gregorian alone, consider giving both styles, for example by using ((OldStyleDate)). If a date appears without being specified as Old Style or New Style, tagging that date with ((which calendar?)) will add the page to Category:Articles containing ambiguous dates for further attention.
If an article contains Julian calendar dates after 4 October 1582 (as in the October Revolution), or if a start-of-year date other than 1 January was in force in the place being discussed, or both, a footnote should be provided on the first usage, explaining the calendar usage adopted for the article. The calendar usage should be compatible with this guideline.
A simple year–year range is written using an en dash (–, – or ((ndash))), not an em dash, hyphen, or slash; this dash is unspaced (that is, with no space on either side); and the end year is usually given in full:
Although non-abbreviated years are generally preferred, two-digit ending years (1881–82, but never 1881–882 or 1881–2) may be used in any of the following cases: (1) two consecutive years; (2) infoboxes and tables where space is limited (using a single format consistently in any given table column); and (3) in certain topic areas if there is a very good reason, such as matching the established convention of reliable sources.[h] For consistency, avoid abbreviated year ranges when they would be used alongside non-abbreviated ranges within an article (or related pages, if in titles). Never use abbreviated years for ranges across centuries (1999–2000, not 1999–00) or for years from the first millennium (886–887, not 886–87).
The slash notation (2005/2006) may be used to signify a fiscal year or other special period, if that convention is used in reliable sources.
Other "simple" ranges use an unspaced en dash as well:
day–day: 5–7January 1979;January5–7, 1979;elections were held March 5–8.
month–month: the 1940 peak period was May–July;the peak period was May–July1940; (but the peak period was May 1940 – July 1940 uses a spaced en dash; see below)
In certain cases where at least one item on either side of the en dash contains a space, then a spaced en dash (((snd))) is used. For example:
between specific dates in different months: They travelled June3 – August18, 1952;They travelled 3June – 18August 1952
between dates in different years:
Charles Robert Darwin (12February 1809 – 19April 1882) was an English naturalist...
Markup: 12((nbsp))February 1809((snd))19((nbsp))April 1882 or 12 February 1809 – 19 April 1882
Abraham Lincoln (February12, 1809 – April15, 1865) was the 16th President of...
between months in different years: The exception was in force August 1892 – January 1903;The Ghent Incursion (March 1822 – January1, 1823) was ended by the New Year's Treaty
Markup: March 1822((snd))January((nbsp))1, 1823 or March 1822 – January 1, 1823
For ranges "to present", the current year (or, in cases where necessary, date) of "present" at the time of writing should be included. Thus 1982–present (as of YYYY) is preferable to just 1982–present, with YYYY being replaced with the year in which you are writing. If the "from" date has an internal space, a spaced en dash is used. Other constructions may be more appropriate in prose (see § Statements likely to become outdated).
In tables and infoboxes where space is limited, pres. may be used (1982–pres.). Do not use incomplete-looking constructions such as 1982– and 1982–... .
Consider adding the ((As of)), or ((Update after)) templates to such constructions, depending on how important it is for editors to keep "present" up to date.
For a person still living: Serena Williams (born September26, 1981) is a..., not (September26, 1981 – ) or (born on September26, 1981).
Do not use * to indicate born; use b. only where space is limited e.g. tables and infoboxes; use either born or b. consistently in any given table column.
Where birthdate is unknown: John Smith (died May1, 1622) or John Smith (died 1622)
Do not use † to indicate died; use d. only where space is limited, with consistency within any given table column.
An overnight period may be expressed using a slash between two contiguous dates: the night raids of 30/31May 1942 or raids of 31May/ 1June 1942.
Or use an en dash: (unspaced) raids of 30–31May 1942; (spaced) raids of 31May – 1June 1942.
Use an en dash, or a word such as from or between, but not both: from 1881 to 1886 (not from 1881–1886);between June1 and July3 (not between June1 – July3)
The ((Age)) template can keep ages current in infoboxes and so on:
The linked forms should not be used on disambiguation pages, and "active" followed by the range is a better alternative for occupations not relating to the composition of works, whether it be musical, grammatical, historical, or any other such work.
When a date is known to be either of two years (e.g. from a regnal or AH year conversion, or a known age at death):
Anne Smith (born 1912 or 1913; died 2013)...
Other forms of uncertainty should be expressed in words, either in article text or in a footnote: April14, 1224 (unattested date). Do not use a question mark (1291?), because it fails to communicate the nature of the uncertainty.
Where c. or a similar form appears which applies only to one of the two endpoints of the range, use a spaced en dash (((snd))).
Examples: 1896 – after 1954, 470 – c. 540, c. 470 – 540, c. 470 – c. 540.
Where a modifier applies to the range as a whole, such as fl. and r., use a spaced or unspaced en dash as appropriate to the range if this modifier is disregarded.
Examples: fl.1571–1588, fl. c. 1600 – 1616, r. c. 1353 – 1336BC, r. 1989–2019CE, r. 2019CE – present.
Some modifiers, such as traditionally, around, BH, and CE, sometimes apply to only one endpoint, and sometimes to the whole range. Whether the en dash should be spaced or unspaced should still be determined by the above guidelines, but consider rephrasing if the result is ambiguous or possibly confusing.
traditionally 1571–1588 and traditionally 1571 – 1588 mean two different things, which may not be obvious to the reader.
traditionally 1585 – c. 1590 can have two different meanings, and which one is meant may not be clear.
400 BCE – 200 clearly has BCE applying only to one endpoint, but the range is ambiguous. Consider using 400–200 BCE, 400 BCE – 200 BCE, or 400 BCE – 200 CE, depending on what is meant.
Technically, Taishō 13 – 57 is currently unambiguous (because there is no Taishō 57), but it is better to use both era designations in this case: Taishō 13 – Shōwa 57.
Ideally a non-breaking space should follow very short modifiers such as c., fl., r., b., and d..
Context determines whether the 12- or 24-hour clock is used. In all cases, colons separate hours, minutes, and (where present) seconds, e.g. 1:38:09pm or 13:38:09. Use figures (11a.m. or 12:45p.m.) rather than words (twelve forty-five p.m.).
12-hour clock times end with lower-case a.m. or p.m., or am or pm, preceded by a non-breaking space, e.g. 2:30p.m. or 2:30pm (markup: 2:30((nbsp))p.m. or 2:30((nbsp))pm), not 2:30p.m. or 2:30pm. Hours should not have a leading zero (e.g. 2:30p.m., not 02:30p.m.). Usually, use noon and midnight rather than 12 pm and 12 am; whether "midnight" refers to the start or the end of a date should be explicitly specified unless clear from the context. Where several times that are all a.m. or all p.m. appear in close proximity, then a.m. or p.m. need be given only once if there is no risk of confusion.
24-hour clock times have no a.m., p.m., noon or midnight suffix, and include a colon (15:30 not 1530). Hours under 10 should have a leading zero (08:15). The time 00:00 refers to midnight at the start of a date, 12:00 to noon, and 24:00 to midnight at the end of a date, but 24 should not be used for the first hour of the next day (e.g. use 00:10 for ten minutes after midnight, not 24:10).
Give dates and times appropriate to the time zone where an event took place. For example, the date of the attack on Pearl Harbor should be December7, 1941 (Hawaii time/date). Give priority to the place at which the event had its most significant effects; for example, if a hacker in Monaco attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. In some cases, the best solution may be to add the date and time in Coordinated Universal Time (UTC). For example:
Rarely, the time zone in which an event took place has since changed; for example, China until 1949 was divided into five time zones, whereas all of modern China is UTC+8. Similarly, the term "UTC" is not appropriate for dates before this system was adopted in 1960;Universal Time (UT) is the appropriate term for the mean time at the prime meridian (Greenwich) when it is unnecessary to specify the precise definition of the time scale. Be sure to show the UTC or offset appropriate to the clock time in use at the time of the event, not the modern time zone, if they differ.
Days of the week
Where space is limited (e.g. tables), days of the week may be abbreviated as Sun, Mon, Tue, Wed, Thu, Fri, Sat (without dots i.e. not Sun., Mon., etc.).
Generally, seasons are uncapitalized (a hot summer) except when personified: Old Man Winter.
Avoid the use of seasons to refer to a particular time of year (winter 1995) as such uses are ambiguous: the seasons are six months apart in the northern and southern hemispheres; winter in the northern hemisphere spans two calendar years, as does summer in the southern hemisphere; and areas near the equator have only wet and dry seasons. Unambiguous alternatives include early 1995; the first quarter of 1995; January to March 1995; spent the southern summer in Antarctica.
Referring to a season by name is appropriate when it is part of a formal or conventional name or designation (annual mid-winter festival; the autumn harvest; 2018 Winter Olympics; Times Fall Books Supplement; details appeared in Quarterly Review, Summer 2015; the court's winter term).
To refer to a decade as a chronological period per se (not with reference to a social era or cultural phenomenon), always use four digits as in the1980s. Do not use the1980's, the1980‑ies, or the1980s' (unless a possessive is actually meant).
Prefixes should be hyphenated (themid‑1980s;pre‑1960s social attitudes).
Adjectives should not be hyphenated (the late 1950s, the early 1970s).
For a social era or cultural phenomenon associated with a particular decade:
Two digits (with a preceding apostrophe) may be used as an alternative to four digits, but only in well-established phrases seen in reliable sources: theRoaring'20s; theGay'90s; condemning the '60s counterculture — but grew up in 1960s Boston, moving to Dallas in1971. Do not write: the90's; the90s; or the90s'.
A third alternative (where seen in reliable sources) is to spell the decade out, capitalized: changing attitudes of the Sixties.
The sequence of numbered years in dates runs ...2BC, 1BC, 1AD, 2AD...; there is no "year zero".
Treat the 1st century AD as years 1–100, the 17th century as 1601–1700, and the second millennium as 1001–2000; similarly, the 1st century BC/BCE was 100–1 BC/BCE, the 17th century BC/BCE was 1700–1601 BC/BCE, and the second millennium 2000–1001 BC/BCE.
Centuries and millennia are identified using either Arabic numerals (the 18th century) or words (the second millennium), with in-article consistency (MOS:ORDINAL notwithstanding). When used adjectivally they contain a hyphen (nineteenth-century painting or 19th-century painting). Do not use superscripts (19th century).
Do not capitalize (the best Nineteenth-century paintings;during the Nineteenth Century)
When the term is frequent, combine yr(years) or ya(years ago) with k(thousand): kya, kyr; M(million): Mya, Myr; and b(short-scale billion): bya, byr. (See Year § Abbreviations yr and ya for more information.)
In academic contexts, SI annus-based units are often used: ka(kiloannus), Ma(megaannus), and Ga(gigaannus). (See Year § SI prefix multipliers for more information.)
Show the meaning parenthetically, and consider linking to the appropriate section of the Year article (Year § Abbreviations yr and ya or Year § SI prefix multipliers) on first occurrence and where the use is a standalone topic of interest. In source quotations, use square brackets: "a measured Libby radiocarbon date of 35.1Mya [million years ago] required calibration..."
Information on specific situations is scattered elsewhere on this page.
Generally, in article text:
Integers from zero to nine are spelled out in words.
Integers greater than nine expressible in one or two words may be expressed either in numerals or in words (16 or sixteen, 84 or eighty-four, 200 or two hundred). When written as words, numbers from 21 to 99 are hyphenated (including when part of a larger number): fifty-six or fifty-six thousand but fivehundred or fivethousand.
Other numbers are given in numerals (3.75, 544) or in forms such as 21million (or billion, trillion, etc. – but rarely thousand). Markup: 21((nbsp))million
Billion and trillion are understood to represent their short-scale values of 109(1,000,000,000) and 1012(1,000,000,000,000), respectively. Keep this in mind when translating articles from non-English or older sources.
M (unspaced, capitalized) or bn (unspaced), respectively, may be used for "million" or "billion" after a number, when the word has been spelled out at the first occurrence (Her estate of £61million was split among her husband (£1M), her son (£5M), her butler (£10M), and her three Weimaraners (£15M each).).
SI prefixes and symbols, such as mega-(M), giga-(G) and tera-(T), should be used only with units of measure as appropriate to the field and not to express large quantities in other contexts. Examples of misuse: In a population of 1.3Gpeople, 300megadeaths would be expected.
When it is done anyway, for contextually important reasons, link the first spelled-out instance of each quantity (e.g. [[crore]], which yields: crore). If no instances are spelled out, provide a note after the first instance, directing the reader to the article about the numbering system.
Provide a conversion to Western numbers for the first instance of each quantity (the templates ((lakh)) and ((crore)) may be used for this purpose), and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write three crore (thirty million). When converting a currency amount, use the exchange rate that applied at the time being written about; the ((INRConvert)) template can be used for this purpose.
The variety of English does not uniquely determine the method of numbering in an article. Other considerations – such as conventions used in mathematics, science, and engineering – may also apply. The choice and order of formats and conversions is a matter of editorial discretion and consensus at the article.
Use: There were many matches; 23 ended in a draw. Or: There were many matches. Twenty-three ended in a draw.
Not: There were many matches. 23 ended in a draw.
Use: No elections were held in 1945 and 1950.
Not: 1945 and 1950 had no elections. (Nor: Nineteen forty-five and 1950 had no elections – comparable numbers should be both written in words or both in figures.)
In tables and infoboxes, quantities are expressed in figures (Years in office:5); but numbers within a table's explanatory text and comments follow the general rule.
Numbers in mathematical formulae are never spelled out (3 < π < 22/7 not three < pi < twenty-two sevenths), and "numbers as numbers" are rarely spelled out in other mathematical contexts (the first three primes are 2, 3, and 5 not the first three primes are two, three, and five; but zero-sum game and roots of unity).
Sport scores and vote tallies should be given as figures, even if in the zero-to-nine range (a 25–7 victory; and passed with 7 ayes, 2 nays, and 1 abstention).
Comparable values nearby one another should be all spelled out or all in figures, even if one of the numbers would normally be written differently: patients' ages were five, seven, and thirty-two or ages were5, 7, and32, but not ages were five, seven, and 32.
Similar guidance applies where "mixed units" are used to represent a single value (as is often done with time durations, and in the imperial and US customary systems): 5 feet 11 inches tall; five feet eleven inches tall; 3 minutes 27 seconds; three minutes twenty-seven seconds.
Adjacent quantities not comparable should ideally be in different formats:twelve 90-minute volumes or 12 ninety-minute volumes, not 12 90-minute volumes or twelve ninety-minute volumes.
Avoid awkward juxtapositions: On February 25, 2011, twenty-one more were chosen, not On February 25, 2011, 21 more were chosen.
Sometimes figures and words carry different meanings; for example, Every locker except one was searched implies there is a single exception (without specifying which), while Every locker except1 was searched means that locker number1 was the only locker not searched.
In English text, do not use a dot (.) or the ordinal indicator (º). The masculine º or feminine ª ordinal indicator is acceptable in names, quotations, etc. from languages that conventionally use it. An Italian example: 313º Gruppo Addestramento Acrobatico not 313º Acrobatic Training Group or the 313º. Use HTML markup for languages that don't have a special character but conventionally use a superscript, like 2e in French.
Like date ranges, number ranges and page ranges should state the full value of both the beginning and end of the range, separated by an en dash: pp.1902–1911 or entries342–349. Except in quotations, avoid abbreviated forms such as 1902–11 and 342–9, which are not understood universally, are sometimes ambiguous, and can cause inconsistent metadata to be created in citations.
Polls predicted Alice would defeat Bob 74–20 percent, with 6 percent undecided.
Singular versus plural
Nouns following simple fractions are singular (took 1⁄4 dose;net change was −1⁄2 point;3⁄2 dose).
Nouns following mixed numbers are plural (11⁄2 doses;another 43⁄4 miles).
Nouns following the lone, unsigned digit 1 are singular, but those following other decimal numbers (i.e. base-10 numbers not involving fractions) are plural (increased 0.7 percentage points;365.25 days;paid 5 dollars per work hour, 1 dollar per travel hour, 0 dollars per standby hour;increased by 1 point but net change +1 points;net change −1 points;net change 1.0 points).
The same rules apply to numbers given in words (one dose;one and one-half doses;zero dollars;net change of negative one points).
Spelled-out fractions are hyphenated: seven-eighths.
Where numerator and denominator can each be expressed in one word, a fraction is usually spelled out (e.g. a two-thirds majority; moved one-quarter mile); use figures if a fraction appears with a symbol (e.g. 1⁄4mi – markup: ((frac|1|4)) mi, not a quarter of a mi or one-quarter mi). A common exception is a series of values: The distances were 1+1⁄4, 2⁄3 and 1⁄2 mile, respectively.
Mixed numbers are usually given in figures, unspaced (not Fellini's film 81⁄2 or 8-1⁄2 but Fellini's film 8+1⁄2 – markup: ((frac|8|1|2))). In any case the integer and fractional parts should be consistent (not nine and1⁄2).
Metric (SI) measurements generally use decimals, not fractions (5.25mm, not 51⁄4mm).
Non-metric (imperial and US customary) measurements may use fractions or decimals (51⁄4inches;5.25inches); the practice of reliable sources should be followed, and within-article consistency is desirable.
In science and mathematics articles, mixed numbers are rarely used (use 4/3 the original rather than 11/3 times the original voltage). The use of ((frac))is discouraged in favor of one of these styles:
STEM articles tend to prefer ASCII characters for fractions in titles, such as Spin-1/2 and this is also preferred where other fractions are needed, like 1/2 + 1/4 + 1/8 + 1/16 + ⋯.
Ordinal suffixes such as -th should not be used with fractions expressed in figures (not each US state has 1/50th of the Senate's votes; 1/8th mile, but one-fiftieth of the Senate's votes; 1/8 mile; one-eighth mile).
Dimensionless ratios (i.e. those without accompanying units) are given by placing a colon between integers, or placing to between numbers-as-words: favored by a 3:1 ratio or a three-to-one ratio, not a 3/1 ratio or a 3–1 ratio.
Use a colon (spaced) when one or more decimal points is present (a 3.5 : 1 ratio – markup:a 3.5 : 1 ratio).
Do not use the colon form where units are involved (dissolve using a 3 ml : 1 g ratio)—instead see ratios section of table at § Unit names and symbols, below.
Numbers between −1 and +1 require a leading zero (0.02, not .02); exceptions are sporting performance averages (.430 batting average) and commonly used terms such as .22caliber.
Indicate repeating digits with an overbar e.g. 14.31((overline|28)) gives 14.3128. (Consider explaining this notation on first use.) Do not write e.g. 14.31(28) because it resembles notation for uncertainty.
Digits are grouped both sides of the decimal point (e.g. 6543210.123456; 520.01234 °C; 101325/760).
Digits are generally grouped into threes. Right of the decimal point, usual practice is to have a final group of four in preference to leaving an "orphaned" digit at the end (99.1234567, but 99.1234567 would also be acceptable). In mathematics-oriented articles long strings may be grouped into fives (e.g. 3.14159265358979323846...).
This style is especially recommended for articles related to science, technology, engineering or mathematics, though in these contexts there may be cases in which grouping confuses rather than clarifies. (For example, for fractions written in horizontal format, adding spaces to a fraction like 123456/127 would cause it to be misread as 123456/127 or 123456/127.)
Markup: Templates ((val)) or ((gaps)) may be used to produce this formatting. Note that use of any space character as a separator in numbers, including non-breaking space, is problematic for screen readers. (See § Non-breaking spaces.) Screen readers read out each group of digits as separate numbers (e.g. 30((thin space))000 is read as "thirty zero zero zero".)
Delimiting style should be consistent throughout a given article.
Either use commas or narrow gaps, but not both in the same article.
Either group the thousands in a four-digit number or do not, but not mixed use in the same article.
However, grouping by threes and fives may coexist.
Four-digit page numbers and four-digit calendar years should never be grouped (not sailed in 1,492, but dynasty collapsed around 10,400 BC or by 13727 AD, Vega will be the northern pole star).
In the body of non-scientific/non-technical articles, percent (American English) or per cent (British English) are commonly used: 10 percent; ten percent; 4.5 per cent. Ranges are written ten to twelve per cent or ten to twelve percent, not ten–twelve per cent.
In the body of scientific/technical articles, and in tables and infoboxes of any article, the symbol % (unspaced) is more common: 3%, not 3% or three%. Ranges: 10–12%, not 10%–12% or 10 to 12%.
When expressing the difference between two percentages, do not confuse a percentage change with a change in percentage points.
Scientific and engineering notation
Scientific notation always has a single nonzero digit to the left of the point: not 60.22×1022, but 6.022×1023.
Avoid mixing scientific and engineering notations (A 2.23×102 m2 region covered by 234.0×106 grains of sand).
In a table column (or other presentation) in which all values can be expressed with a single power of 10, consider giving e.g. ×107 once in the column header, and omitting it in the individual entries. (Markup: ((e|7)))
In both notations, the number of digits indicates the precision. For example, 5×103 means rounded to the nearest thousand; 5.0×103 to the nearest hundred; 5.00×103 to the nearest ten; and 5.000×103 to the nearest unit.
Markup: ((val)) and ((e)) may be used to format exponential notation.
Polls estimated Jones's share of the vote would be 55 percent, give or take about 3 percent
Markup: ((+-)), ((su)), and ((val)) may be used to format uncertainties.
Where explicit uncertainty is unavailable (or is unimportant for the article's purposes) round to an appropriate number of significant digits; the precision presented should usually be conservative. Precise values (often given in sources for formal or matter-of-record reasons) should be used only where stable and appropriate to the context, or significant in themselves for some special reason.
The speed of light is defined to be 299,792,458m/s
butParticle velocities eventually reached almost two-thirds the 300-million-metre-per-second speed of light.
checks worth $250 (equivalent to $1,800 in 2016) (not $1,845.38 in 2016)
The city's 1920 population was 10,000 (not population was 9,996 – an official figure unlikely to be accurate at full precision)
butThe town was ineligible because its official census figure (9,996) fell short of the statutory minimum of ten thousand (unusual case in which the full-precision official figure is truly informative)
The accident killed 337 passengers and crew, and 21 people on the ground (likely that accurate and precise figures were determined)
At least 800 persons died in the ensuing mudslides (unlikely that any precise number can be accurate, even if an official figure is issued)
or Officials listed 835 deaths, but the Red Cross said dozens more may have gone unreported (in reporting conflicting information, give detail sufficient to make the contrast intelligible)
The jury's award was $8.5million (not $8,462,247.63). The appeals court reduced this to $3,000,001 (one dollar in actual damages, the remainder in punitive damages).
The number of decimal places should be consistent within a list or context (The response rates were 41.0 and 47.4 percent, respectively, not 41 and 47.4 percent), unless different precisions are actually intended.
It may sometimes be appropriate to note the lack of uncertainty information, especially where such information is normally provided and necessary for full interpretation of the figures supplied.
A local newspaper poll predicted 52 percent of the vote would go to Smith, but did not include information on the uncertainty of this estimate
The ((undue precision)) template may be added to figures appearing to be overprecise.
Avoid using "approximately", "about", and similar terms with figures that have merely been approximated or rounded in a normal and expected way, unless the reader might otherwise be misled.
The tallest player was 6 feet 3 inches (not ... about 6 feet 3 inches – heights are conventionally reported only to the nearest inch, even though greater precision may be available in principle)
butThe witness said the assailant was about 5 feet 8 inches tall ("about" because here the precise value is unknown, with substantial uncertainty)
The reader may be assumed to interpret large round numbers (100,000 troops) as approximations. Writing a quantity in words (one hundred thousand troops) can further emphasize its approximate nature.
In computer-related articles, use the prefix 0x for hexadecimal and 0b for binary,[j] unless there is a strong reason to use some other notation.[k] Explain these prefixes in the article's introduction or on first use.
In all other articles, use base: 1379, 2013. Markup: ((base|137|9)), ((base|201|3))
For bases above 10, use symbols conventional for that base (as seen in reliable sources) e.g. for base 16 use 0–9 and A–F.
For octal, use 2008. Avoid using a prefix unless it is needed for computer code samples, in which case explain the prefix on first use.
Quantities are typically expressed using an appropriate "primary unit", displayed first, followed, when appropriate, by a conversion in parentheses e.g. 200 kilometres (120 mi). For details on when and how to provide a conversion, see the section § Unit conversions. The choice of primary units depends on the circumstances, and should respect the principle of "strong national ties", where applicable:
In non-scientific articles with strong ties to the United States, the primary units are US customary (pounds, miles, feet, inches, etc.)
In non-scientific articles with strong ties to the United Kingdom, the primary units for most quantities are metric or other internationally used units,[l] except that:
UK engineering-related articles, including those on bridges and tunnels, generally use the system of units in which the subject project was drawn up (but road distances are given in imperial units, with a metric conversion – see next bullet);
the primary units for distance/length, speed and fuel consumption are miles, miles per hour, and miles per imperial gallon (except for short distances or lengths, where miles are too large for practical use);
the primary units for personal height and weight are feet/inches and stones/pounds;
imperial pints are used for quantities of draught beer/cider and bottled milk;
Quantities set via definition (as opposed to measured quantities) should be given first in the units used in the definition, even if this makes the structure of presentation inconsistent: During metrication, the speed limit was changed from 30mph (48km/h) to 50km/h (31mph).
Or use about to emphasize which is the statutory, exact value: ...from 30mph (about 48km/h) to 50km/h (about 31mph).
Nominal quantities (e.g. 2×4lumber) require consideration of whether the article is concerned with the item's actual dimensions or merely with its function. In some cases, the nominal quantity may suffice; in others it may be necessary to give the nominal size (often in non-SI units), the actual size in non-SI units, and the actual size in SI units.
Whenever a conversion is given, the converted quantity's value should match the precision of the source (see § Unit conversions).
Where the article's primary units differ from the units given in the source, the ((convert)) template's |order=flip flag can be used; this causes the original unit to be shown as secondary in the article, and the converted unit to be shown as primary: ((convert|200|mi|km|order=flip)) → The two cities are 320 kilometres (200 mi) apart.
Where English-speaking countries use different units for the same quantity, provide a conversion in parentheses: the Mississippi River is 2,320 miles (3,734 km) long; the Murray River is 2,508 kilometres (1,558 mi) long. But in science-related articles, supplying such conversion is not required unless there is some special reason to do so.
Where an imperial unit is not part of the US customary system, or vice versa – and in particular, where those systems give a single term different definitions – a double conversion may be appropriate: Rosie weighed 80 kilograms (180 lb; 12 st 8 lb) (markup: ((convert|80|kg|lb stlb))); The car had a fuel economy of 5 L/100 km (47 mpg‑US; 56 mpg‑imp) (markup: ((convert|5|L/100km|mpgus mpgimp|abbr=on))).
Generally, conversions to and from metric units and US or imperial units should be provided, except:
When inserting a conversion would make a common or linked expression awkward (The four-minute mile).
In some topic areas (for example maritime subjects where nautical miles are the primary units, or American football where yards are primary) it can be excessive to provide a conversion for every quantity. In such cases consider noting that the article will use a particular unit – possibly giving the conversion factor to other, familiar units in a parenthetical note or a footnote – and link the first occurrence of each unit but not give a conversion every time it occurs. Applying this principle may require editorial discretion; for example, in scientific articles the expected level of reader sophistication should be taken into account.
Converted quantity values should use a level of precision similar to that of the source quantity value, so the Moon is 380,000kilometres (240,000mi) from Earth, not (236,121mi). Small numbers, especially if approximate, may need to be converted to a range where rounding would cause a significant distortion, so about one mile (1–2km), not about one mile (2km). Be careful especially when your source has already converted from the units you're now converting back to. This may be evidenced by multiples of common conversion factors in the data, such as 160 km (from 100 miles). See false precision.
In a direct quotation, always retain the source units. Any conversions can be supplied either in the quote itself (in square brackets, following the original measurement) or in a footnote. See footnoting and citing sources.
((Units attention)) may be added to articles needing general attention regarding choice of units and unit conversions.
Examples of unit names: foot, metre, kilometre, (US: meter, kilometer).
Examples of unit symbols: ft, m, km.
Unit names and symbols should follow the practice of reliable sources.
In prose, unit names should be given in full if used only a few times, but symbols may be used when a unit (especially one with a long name) is used repeatedly, after spelling out the first use (e.g. Up to 15 kilograms of filler is used for a batch of 250kg).
Exception: Certain units are generally represented by their symbols (e.g. °C rather than degrees Celsius) even on first use, though their unit names may be used for emphasis or clarity (conversion of degrees Celsius to degrees Fahrenheit).
Exception: Consider using inches (but not in.) in place of in where the latter might be misread as a preposition—but not where the value is followed by a parenthesized conversion e.g. bolts 5 in (12.7 cm) long, or is part of such a conversion (bolts 12.7 cm (5 in) long).
Where space is limited, such as in tables, infoboxes, parenthetical notes, and mathematical formulas, unit symbols are preferred.
Units unfamiliar to general readers should be presented as a name–symbol pair on first use, linking the unit name (Energies rose from 2.3 megaelectronvolts (MeV) to 6MeV).
Ranges use unspaced en dash (((ndash))) if only one unit symbol is used at the end (e.g. 5.9–6.3kg), and spaced en dash (((snd))) if two symbols are used (e.g. 3μm – 1mm); ranges in prose may be specified using either unit symbol or unit names, and units may be stated either after both numerical values or after the last (all acceptable: from 5.9 to 6.3 kilograms; from 5.9 kilograms to 6.3 kilograms; from 5.9 to 6.3kg; from 5.9kg to 6.3kg).
Length–width, length–width–height and similar dimensions may be separated by the multiplication sign (× or ×) or the word by.
The × symbol is preceded by a space (preferably non-breaking), and followed by a space (which may also be non-breaking in short constructions), and each number should be followed by a unit name or symbol:
1 m × 3 m × 6 m, not 1 × 3 × 6 m, (1 × 3 × 6) m, nor 1 × 3 × 6 m3
a metal plate 1 ft × 3 ft × 0.25 in
a railroad easement 10 ft × 2.5 mi
With by, the unit need be given only once if it is the same for all dimensions: 1 by 3 by 6 metres or 1 by 3 by 6 m
The unspaced letter x may be used in common terms such as 4x4.
General guidelines on use of units
Unit names and symbols
Except as listed in the § Specific units table below, unit symbols are uncapitalized unless they are derived from a proper name, in which case the first letter (of the base unit symbol, not of any prefix) is capitalized.[m]
8 kg 100 kPa
8 Kg 100 kpa
Unit symbols are undotted.
38 cm of rope
38 cm. of rope
Unit names are given in lower case except: where any word would be capitalized, or where otherwise specified in the SI brochure or this Manual of Style.
Used in aviation contexts for aircraft and wind speeds, and also used in some nautical and general meteorological contexts. When applied to aircraft speeds, kn means KIAS unless stated otherwise; if kn is used for calibrated airspeed, equivalent airspeed, true airspeed, or groundspeed, explicitly state and link to, upon first use, the type of speed being referred to (for instance, kn equivalent airspeed, or, if severely short of space, kn EAS); for airspeeds other than indicated airspeed, the use of the specific abbreviation for the type of airspeed being referred to (such as KEAS) is preferred. When referring to indicated airspeed, either kn or KIAS is permissible. Groundspeeds and wind speeds must use the abbreviation kn only.
Markup: μm Link to micrometre (for which micron is a synonym) on first use.
The qualifier t or troy must be specified where applicable. Use the qualifier avdp (avoirdupois) only where there is risk of confusion with troy ounce, imperial fluid ounce, US fluid ounce, or troy pound; but articles about precious metals, black powder, and gemstones should always specify which type of ounce (avoirdupois or troy) is being used, noting that these materials are normally measured in troy ounces and grams.
Markup: °. Use a non-breaking space: 12((nbsp))°C, not 12°C nor 12°((nbsp))C(12°C, not 12°C nor 12°C). Do not use the precomposed charactersU+2103℃DEGREE CELSIUS and U+2109℉DEGREE FAHRENHEIT.
In certain subject areas, calorie is conventionally used alone; articles following this practice should specify on first use whether the use refers to the small calorie or to the kilocalorie (large calorie). Providing conversions to SI units (usually calories to joules or kilocalories to kilojoules) may also be useful. A kilocalorie (kcal) is 1000 calories. A calorie (small calorie) is the amount of energy required to heat 1 gram of water by 1°C. A kilocalorie is also a kilogram calorie.
In quantities of bits and bytes, the prefixes kilo- (symbol k or K), mega- (M), giga- (G), tera- (T), etc., are ambiguous in general usage. The meaning may be based on a decimal system (like the standard SI prefixes), meaning 103, 106, 109, 1012, etc., or it may be based on a binary system, meaning 210, 220, 230, 240, etc. The binary meanings are more commonly used in relation to solid-state memory (such as RAM), while the decimal meanings are more common for data transmission rates, disk storage and in theoretical calculations in modern academic textbooks.
Follow these recommendations when using these prefixes in Wikipedia articles:
Following the SI standard, a lower-case k should be used for "kilo-" whenever it means 1000 in computing contexts, whereas a capital K should be used instead to indicate the binary prefix for 1024 according to JEDEC. If, under the exceptions detailed further below, the article otherwise uses IEC prefixes for binary units, use Ki instead.
Do not assume that the binary or decimal meaning of prefixes will be obvious to everyone. Explicitly specify the meaning of k and K as well as the primary meaning of M, G, T, etc. in an article (((BDprefix)) is a convenient helper). Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.
The definition most relevant to the article should be chosen as primary for that article, e.g. specify a binary definition in an article on RAM, decimal definition in an article on hard drives, bit rates, and a binary definition for Windows file sizes, despite files usually being stored on hard drives.
Where consistency is not possible, specify wherever there is a deviation from the primary definition.
Disambiguation should be shown in bytes or bits, with clear indication of whether in binary or decimal base. There is no preference in the way to indicate the number of bytes and bits, but the notation style should be consistent within an article. Acceptable examples include:
A 64MB (64×10242-byte) video card and a 100GB (100×10003-byte) hard drive
A 64MB (64×220-byte) video card and a 100GB (100×109-byte) hard drive
A 64MB (67,108,864-byte) video card and a 100GB (100,000,000,000-byte) hard drive
Avoid combinations with inconsistent form such as A 64MB (67,108,864-byte) video card and a 100GB (100×10003-byte) hard drive. Footnotes, such as those seen in Power Macintosh 5500, may be used for disambiguation.
Unless explicitly stated otherwise, one byte is eight bits (see Byte § History).
The IEC prefixeskibi- (symbol Ki), mebi- (Mi), gibi- (Gi), etc., are generally not to be used except:[n]
when the majority of cited sources on the article topic use IEC prefixes;
in a direct quote using the IEC prefixes;
when explicitly discussing the IEC prefixes; or
in articles in which both types of prefix are used with neither clearly primary, or in which converting all quantities to one or the other type would be misleading or lose necessary precision, or declaring the actual meaning of a unit on each use would be impractical.
In country-specific articles, such as Economy of Australia, use the currency of the subject country.
In non-country-specific articles such as Wealth, use US dollars (US$123 on first use, generally $123 thereafter), euros (€123), or pounds sterling (£123).
Do not capitalize the names or denominations of currencies, currency subdivisions, coins and banknotes: not a Five-Dollar bill, four Quarters, and one Penny total six Dollars one Cent but a five-dollar bill, four quarters, and one penny total six dollars one cent. Exception: where otherwise required, as at the start of a sentence or in such forms as Australian dollar.
In general, the first mention of a particular currency should use its full, unambiguous signifier (e.g. A$52), with subsequent references using just the appropriate symbol (e.g. $88), unless this would be unclear. Exceptions:
In an article referring to multiple currencies represented by the same symbol (e.g. the dollars of the US, Canada, Australia, New Zealand, and other countries – see Currency symbols § dollar variants) use the full signifier (e.g. US$ or A$, but not e.g. $US123 or $123 (US)) each time, except (possibly) where a particular context makes this both unnecessary and undesirable.
In articles entirely on EU-, UK- and/or US-related topics, all occurrences may be shortened (€26, £22 or $34), unless this would be unclear.
For the British pound sterling (GBP), use the £ symbol with one horizontal bar (U+00A3£POUND SIGN), not the double-barred ₤ symbol (U+20A4₤LIRA SIGN). (Whether a pound sign uses one or two bars is purely a type-design choice.) For non-British currencies that use "pounds", use the symbol or abbreviation conventionally employed for that currency, if any.
Do not place a currency symbol after the accompanying numeric figures (e.g. 123$, 123£, 123€) unless that is the normal convention for that symbol when writing in English: smaller British coins include 1p, 2p, and 5p denominations.
Currency abbreviations preceding a numeric value are unspaced if they consist of a nonalphabetic symbol alone (£123 or €123), or end with a nonalphabetic symbol (R$123); but spaced (using ((nbsp))) if completely alphabetic (R 123 or JD 123).
Ranges should be expressed giving the currency signifier just once: $250–300, not $250–$300.
million and billion should be spelled out on first use, and (optionally) abbreviated M or bn (both unspaced) thereafter: She received £70 million and her son £10M; the school's share was $250–300 million, and the charity's $400–450 M.
In general, a currency symbol should be accompanied by a numeric amount e.g. not He converted his US$ to A$ but He converted his US dollars to Australian dollars or He exchanged the US$100 note for Australian dollars.
Exceptions may occur in tables and infoboxes where space is limited e.g. Currencies accepted: US$, SFr, £, €. It may be appropriate to wikilink such uses, or add an explanatory note.
Conversions of less-familiar currencies may be provided in terms of more familiar currencies – such as the US dollar, euro or pound sterling – using an appropriate rate (which is often not the current exchange rate). Conversions should be in parentheses after the original currency, along with the convert-to year; e.g. the grant in 2001 was 10,000,000 Swedish kronor ($1.4M, €970,000, or £850,000 as of 2009[update])
For obsolete currencies, provide an equivalent (formatted as a conversion) if possible, in the modern replacement currency (e.g. decimal pounds for historical pre-decimal pounds-and-shillings), or a US-dollar equivalent where there is no modern equivalent.
In some cases, it may be appropriate to provide a conversion accounting for inflation or deflation over time. See ((Inflation)) and ((Inflation-fn)).
When converting among currencies or inflating/deflating, it is rarely appropriate to give the converted amount to more than three significant figures; typically, only two significant figures are justified: the grant in 2001 was 10,000,000 Swedish kronor ($1.4M, €970,000, or £850,000), not ($1,390,570, €971,673 or £848,646)
The Insert menu below the editing window gives a more complete list of math symbols, and allows symbols to be inserted without the HTML encoding (e.g. ÷) shown here.
Spaces are placed to left and right when a symbol is used with two operands (the sum 4 + 5), but no space is used when there is one operand (the value +5). Exception: spaces are usually omitted in inline fractions formed with /: 3/4 not 3 / 4.
The ((mvar)) (for single-letter variables) and ((math)) (for more complicated expressions) templates are available to display mathematical formulas in a manner distinct from surrounding text.
The ((nbsp)) and ((nowrap)) templates may be used to prevent awkward linebreaks.
"title" means that the coordinates will be displayed next to the article's title at the top of the page (in desktop view only; title coordinates do not display in mobile view) and before any other text or images. It also records the coordinates as the primary location of the page's subject in Wikipedia's geosearch API.
Geographical coordinates on Earth should be entered using a template to standardise the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically.
The ((Coord)) template offers users a choice of display format through user styles, emits a Geo microformat, and is recognised (in the title position) by the "nearby" feature of Wikipedia's mobile apps and by external service providers such as Google Maps and Google Earth, and Yahoo. Infoboxes automatically emit ((Coord)).
The following formats are available.
For degrees only (including decimal values): ((coord|dd|N/S|dd|E/W))
For degrees/minutes: ((coord|dd|mm|N/S|dd|mm|E/W))
For degrees/minutes/seconds: ((coord|dd|mm|ss|N/S|dd|mm|ss|E/W))
dd, mm, ss are the degrees, minutes and seconds, respectively;
N/S is either N for northern or S for southern latitudes;
E/W is either E for eastern or W for western longitudes;
negative values may be used in lieu of S and W to denote Southern and Western Hemispheres
For the city of Oslo, located at 59° 54′ 50″ N, 10° 45′ 8″ E:
Generally, the larger the object being mapped, the less precise the coordinates should be. For example, if just giving the location of a city, precision greater than degrees (°), minutes (′), seconds (″) is not needed, which sufficient to locate, for example, the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10meters or even one meter in some cases (1″ ~15m to 30m, 0.0001° ~5.6m to 10m).
^All-numeric yyyy-mm-dd dates might be assumed to follow the ISO 8601 standard, which mandates the Gregorian calendar. Also, technically all years must have (only) four digits, but Wikipedia is unlikely to ever need to format a date beyond the year 9999.
^These formats cannot, in general, be distinguished on sight, because there are usages in which 03-04-2007 represents March4, and other usages in which it represents April3. In contrast, there is no common usage in which 2007-04-03 represents anything other than April3.
^The calendar practices of Oxford Dictionary of National Biography and Encyclopædia Britannica can be inferred by looking up the birth and death dates of famous, well-documented individuals.
^A change from a preference for two digits, to a preference for four digits, on the right side of year–year ranges was implemented in July 2016 per this RFC.
^The number in parentheses in a construction like 1.604(48) × 10−4 J is the numerical value of the standard uncertainty referred to the corresponding last digits of the quoted result.
^One such situation is with Unicode codepoints, which use U+; U+26A7, not 0x26A7.
^If there is disagreement about the primary units used in a UK-related article, discuss the matter on the article talk-page or at Wikipedia talk:Manual of Style/Dates and numbers (WT:MOSNUM). If consensus cannot be reached, refer to historically stable versions of the article and retain the units used in these as the primary units. Also note the style guides of British publications (e.g. The Times, under "Metric").
^These definitions are consistent with all units of measure mentioned in the SI Brochure and with all units of measure catalogued in EU directive 80/181/EEC.
^Wikipedia follows common practice regarding bytes and other data traditionally quantified using binary prefixes (e.g. mega- and kilo-, meaning 220 and 210 respectively) and their unit symbols (e.g. MB and KB) for RAM and decimal prefixes for most other uses. Despite the IEC's 1998 international standard creating several new binary prefixes (e.g. mebi-, kibi-, etc.) to distinguish the meaning of the decimal SI prefixes (e.g. mega- and kilo-, meaning 106 and 103 respectively) from the binary ones, and the subsequent incorporation of these IEC prefixes into the ISO/IEC 80000, consensus on Wikipedia in computing-related contexts favours the retention of the more familiar but ambiguous units KB, MB, GB, TB, PB, EB, etc. over use of unambiguous IEC binary prefixes. For detailed discussion, see WT:Manual of Style (dates and numbers)/Archive/Complete rewrite of Units of Measurements (June 2008).
^Garraty, John A.; Carnes, Mark C., eds. (1999). "Editorial note". American National Biography. Oxford University Press. pp. xxi–xxii.