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Back in high school English, you probably learned how to add footnotes and endnotes to essays and papers. If you didn't add information about your sources, your paper would get a very low grade.

Wikipedia's equivalent of a failing grade is to have another editor revert your edit, putting the article back to exactly as it was before you changed it. If you want to add new information to articles and have it stay there, you need to understand Wikipedia's rules. This chapter explains those rules. If you follow them, you'll help ensure the accuracy and credibility of Wikipedia articles.

To add a source (what Wikipedia calls citing a source), you also need to learn some technical matters—how Wikipedia software handles external links, and how it creates footnotes. This chapter includes two tutorials that show you how to create links and footnotes that would make your English teacher proud.

Wikipedia is not the place to document the previously undocumented, to report new discoveries, to publish new theories, or to record personally observed events that may be considered newsworthy. Such content may well be true, but as far as Wikipedia's policies are concerned, true isn't enough. Information must be verifiable, which means it must be backed by a reliable, published source outside Wikipedia. Simply put, Wikipedia must never be the first place that news appears. If a tree falls in a forest and it's not reported elsewhere, then Wikipedia isn't going to report it either.

Here are Wikipedia's documentation rules in brief:

• What you know is true (or, more accurately, what you think is true) isn't a criterion for what you can assert on Wikipedia. Information must come from a published, reliable source.
• Ideally, always cite your source when you add new information to Wikipedia. If you add a quotation, or if you add something that is likely to be challenged, you absolutely must cite a published, reliable source.

Wikipedia has three core policies for content. Chapter 1: Editing for the first time discussed one of them—Neutral point of view (see the section about content). The other two policies are mostly about new content: No original research and Verifiability. You can (and probably should) read those two policies yourself. The shortcuts are WP:NOR and WP:V; on any Wikipedia page, just type one of those into the search box on the left, and then click Go. Misunderstandings of these policies abound. The rest of this section is devoted to clearing up some of the biggest.

Not all sources are created equal

Only reliable sources hold up to the scrutiny of the Wikipedia community. But what makes a source reliable? To quote from Wikipedia's Reliable sources guideline (shortcut: WP:RS): "Articles should rely on reliable, third-party published sources with a reputation for fact-checking and accuracy." Most international and national newspapers, magazines, and scientific journals put significant resources into avoiding mistakes, to maintain their credibility and readership (and their survival in the face of libel and other lawsuits). On the other hand, an anonymous blogger can feel pretty free to post anything on the Web without worrying about the consequences. The general rule is: "Self-published books, personal Web sites, and blogs are largely not acceptable as sources." (Wikipedia:Verifiability)

If after reading this chapter you are still unsure whether a source is reliable, be sure to read the Reliable sources guideline. If you remain unsure, try asking at the Reliable sources noticeboard (shortcut: WP:RS/N).

Some sources apply only in specific, limited circumstances

Now that you've got the concept of reliability drilled into you, you should know about two situations where otherwise "unreliable" information can appear in Wikipedia articles:

• Material from self-published and questionable sources may be used as sources in articles about themselves. You should phrase such information as an assertion. For example, say, "According to Elsbeth Wainwright's personal Web site, she was born on a mountain," not simply, "Elsbeth Wainwright was born on a mountain." The fact that a Web site says something is undisputable, and that's the fact you're asserting in this case.
• Editorial opinions in newspapers aren't the same as news articles, and you should treat them differently. For example, you can say, "The Catfish Gazette opposed the destruction of the historical courthouse," if you read that opinion on the Gazette's editorial page. But you must not use wording that makes it look like opinions are facts. You can't, for example, use an editorial opinion to put something like this into a Wikipedia article: "The destruction of local landmarks in Catfish township in the past 20 years has been a tragedy and a travesty." (Notice also the violation of Neutral point of view.)

You don't have to provide citations for information already sourced

In four situations, you can put specific information into an article without citing a source. Mind you, the information must still be verifiable; you simply don't need to accompany it with a citation in these situations.

1) In the lead section. The initial section of an article should be a concise overview of the article, establishing context, summarizing the most important points, and explaining why the subject is interesting and notable. Citations aren't generally appropriate in the lead section; they belong in the body of the article. (Sometimes you do have to provide citations, if other editors insist.) Figure 2-1 is a good example of a lead section. (Lead sections are discussed in more detail in the section about lead sections.)

2) If a section of an article summarizes what is in another, more detailed article. In Wikipedia, such a section is called summary style, and should be a few paragraphs long. Immediately below the heading of the section is a link to the main article, which contains all the sources. Figure 2-2 shows a section of an article that demonstrates summary style.

3) If there's an internal link to another article. For example, suppose you add this to an article: "Name of person, a historian who has written extensively about this period, said quotation." You don't have to document who this person is, because the reader can follow the internal link to the Wikipedia article about the person. That article, of course, should support your phrase, "a historian who has written extensively about this period." Note that you do have to add a source to document the quotation.

4) If the information in an article is documented in a section at the bottom of the article. Consider an article that is based primarily on books, like George Washington in the American Revolution. In such cases, you can document most of the information by simply listing those books in a "Bibliography" section at the end of the article (Figure 2-3).

You must provide a source for controversial text

If you add potentially contentious information to an article, you absolutely must add a citation immediately following that information, so others can verify it. If you're the one who adds information to an article, the burden of proof rests on you. If another editor questions you about a specific phrase, sentence, or paragraph, the correct response is to cite your source, as a footnote, rather than say, "Find it yourself—I'm sure one of the sources in the article supports what I put in."

Wikipedia considers anything negative about a person or organization to be controversial or contentious. Editors also often challenge causal statements. ("Because the president vetoed the tax cuts, the country went into a recession.") If you add such a statement, it had better come from a reliable source, not your own opinion. When the topic of an article is controversial, other editors may interpret almost any information you add to that article as controversial. But if you always cite a good source that supports the information you're adding, then you can defend yourself if you're accused of adding original research or your personal point of view.

Citing a source doesn't justify copyright violations

Say you've come across an online newspaper article with lots of information you want to add to a Wikipedia article. That's great, but don't just copy and paste large amounts of text—that's a copyright violation. Stick to the facts (facts can't be copyrighted), and recognize that newspapers don't object to small percentages of a story's text ending up in Wikipedia if the newspaper gets credit (via citation), particularly if you provide a link to the full story online. (For a discussion about what you can legally copy in large amounts, see the section about copying other material.)

Much, if not most, of the information in Wikipedia is documented by online sources. In this tutorial, you'll learn how to create a link to such a source. Links to Web pages outside Wikipedia are called external links.

1. On any Wikipedia page, in the search box on the left, type WP:SAND.
2. You're editing in the sandbox (see the section about the sandbox), so you can play around without damaging anything if you make a mistake.

3. At the top of page, click the "edit this page" tab.

   You're now in edit mode. Note the edit box, the Summary box, and the various symbols and markup below the warning that begins "Do not copy." (To double-check whether you're in edit mode, look at Figure 2-4.)

4. Delete all the text in the edit box.

   At the end of this tutorial, you're not going to be saving your edit, so it's okay to delete text such as "Please leave this line alone".

5. Type the following three sentences into the edit box:

   Here's how to create an external link in Wikipedia. [http://www.slate.com/id/2654/]

   Always put brackets around a URL. Here's the URL without the brackets, so you can see what it would look like (remember, this is '''wrong'''): http://www.slate.com/id/2654/

6. Press the Tab key to go to the "Summary" box. (It's just above the "This is a minor edit" and "Watch this page" checkboxes") Type a few words explaining your edit into that box. Then, just below that box, click the "Show preview" button. (See Figure 1-5 if you need a refresher.)

   You see the link you just created, as shown in Figure 2-5.

Wikipedia software automatically numbers external links when they're URLs surrounded by brackets: [1], [2], and so on.

That's all there is to creating external links. If you're going to continue working in this chapter, just keep the sandbox as is; you'll use it again in the footnotes tutorial. Otherwise, close or exit the sandbox page without saving your edit.

Inserting an external link into an article to show where you got information is better than nothing, but by itself it's not the proper way to cite a source. An embedded link (an external link in the middle of an article) isn't a proper citation because links, like milk, have a tendency to go bad over time. Links can stop working when a Web site goes out of business, someone moves or deletes a Web page you linked to, or a URL changes for any number of reasons. When links go bad, so does any substantiation of the sentences that the links were supposed to support.

The best way to reduce the impact of bad links is to fully cite your source, to include more information than just the URL.

How to cite sources

To cite a source, add all the source information into the body of the article, plus special footnote markup. When the Wikipedia software displays the article, it puts a footnote number in the body of the article and the citation information in the "References" section at the bottom. When readers click a footnote number, it takes them to the footnote information at the bottom of the article. (You can learn exactly how to create footnotes in the section about footnotes; also check out Help:Footnotes.)

Two styles of footnotes

As you'll discover as you edit Wikipedia, getting all editors to do everything the same way is like trying to herd a group of cats. It's best to take what the cats prefer to do into account. Wikipedia has policies, which everyone must follow; guidelines, which sometimes provide multiple options; and some things on which there's never been general agreement, so there aren't even guidelines. In practical terms, footnotes fall into that last category.

For example, a survey of 28 Main Page articles in October 2007 found that 12 articles used only regular footnotes, while five used only Harvard-style footnotes. The other 11 articles used a mix of the two. Even then, there wasn't just one style: eight of the 11 used two sections, but three combined the two different footnotes into a single section.

In general, you'll find footnotes appearing in two different ways in fully developed articles:

• Regular footnotes. A footnote number appears in the body of the article, and the full citation information for that footnote appears at the bottom of the article, in a section usually (but not always) called "References."
• Harvard-style footnotes. A footnote number in the body of the article links to a brief citation (author plus page number, or author plus date plus page number) in a "Notes" section. Then full citation information goes in a second section called "References." There's no automated connection for the reader between text in the two sections.

Since Harvard-style footnotes are a variant of regular footnotes, once you've learned regular footnotes, you'll have no problems with the variant. Don't get into a fight over the "right" way to do footnotes. If you're creating or building an article, you can pick a style that suits you; if you're adding to an article with an established style, follow that style.

Getting the most out of sources

Sources are rarely utilized for all they are reliably worth. It is very common for Wikipedia editors to add a citation to source the verifiability of a single fact in an article. Most often the editor has found this source via a search engine, seeking to provide a source for a detail in an article, some pesky tidbit without a citation. This common approach, akin to stopping at the grocery store for eggs and milk and nothing else, rather than "working" the store for an hour with a long shopping list and an eye for bargains, tends to miss many opportunities to improve both article content and sourcing.

Articles with "citation needed" tags often already have sufficient sources that simply have been under-utilized. Most new sources added for a detail or two can also be dug into for additional sourcing value, and the facts they provide may even relate synergistically to information in already-cited sources if they are re-examined in light of the new material.

It is often helpful to make a list (in your own, wiki-coded words) of all the facts reliably provided by a source for a topic you are working on, and see how many of them can be integrated into the article with a single source citation; the number may surprise you.

If you've been paying attention in this chapter so far, you know that if you want to add information to a Wikipedia article, you need to have a reliable source, and you need to cite that source in the Wikipedia article. In the previous section, you also learned that footnotes are the most reliable way to provide your readers with documentation.

Wikipedia has two ways to create footnotes: freeform and citation templates. Citation templates take longer to learn upfront, but they have advantages, as discussed in the section about citation templates.

Creating a simple footnote

1. Open the sandbox for editing.

   If you're not there already, on any Wikipedia page, type WP:SAND into the search box, and then, at the top of page, click the "edit this page" tab. (And if you're in preview mode, that's fine too.)

2. In the sandbox, delete all the text, and then type the following text (see Figure 2-6):

   == Body of the article ==
   
   In 1997, Chrysler was more profitable, with earning of $2.8 billion, than Daimler, which earned $1.8 billion.<ref>Surowiecki, James. [http://www.slate.com/id/2654 "The Daimler-Chrysler Collision: Another Merger in Search of That Elusive Synergy"], ''Slate'' magazine, May 15, 1998, retrieved September 12, 2007</ref>
   
   == References ==
   
   <references/>
   

   

   As shown in Figure 2-6, Wikipedia's footnote system has two distinct parts:

   • Footnote information appears in the body of the article. It must have a ref tag (<ref>) in front and the companion closing tag (</ref>) at the end, to tell the Wikipedia software to treat it like a footnote.
     Tip:

     You don't have to type these two tags. Instead, highlight the text to go in the footnote, then click the icon on the far right of the edit toolbar (see Figure 2-6 for example).
   • There must be a "<references/>" tag somewhere on the page to tell the software exactly where to display all the footnotes. (Notice the ending "/" that is part of this tag is necessary for the footnotes to work correctly.). If no <references/> present, the references will appear at the end of the page.
     Note:

     It doesn't matter if you call the footnotes section "References" (the most common) or "Notes" or "Footnotes" or even "References and Notes." The software doesn't depend on the section name. It's the <references/> tag (or as you'll often see, a ((reflist)) template) that tells the software where to put the footnotes.

3. Type a few words explaining the edit into the Summary box, and click the "Show preview" button.

   If you see what's in Figure 2-7, your footnote is complete.

Now that you know how to create a footnote, remember three points before you head off to start adding citations to articles:

• When you want to edit an existing footnote, remember that the text of that footnote goes in the body of the article, even though Wikipedia displays it in the References section. So don't open the References section to edit that footnote: All you'll see is the section heading and the <references/> tag (or its variant, the ((reflist)) template). To edit an existing footnote, either go into edit mode for the entire article, or preferably go into edit mode for just the section where the text for the footnote is located.
• The footnote number (^[1]) and the displayed footnote are linked. If you click on the upward caret (the "^") in footnote 1, the cursor moves to the ^[1]. (When you do so, the page may jump around a bit; scroll so you're back to seeing the whole page.) Similarly, if you click on the ^[1], the cursor moves to the text for footnote 1 (and shades the whole footnote in light blue). (Try it, using either your preview or any article with footnotes.)
• Near the middle of Figure 2-7, the external link in the references (the title of the referenced article) isn't numbered by the Wikipedia software the way the external link is in the body of the Wikipedia article in Figure 2-5. The reason is that there is both a URL and some following text within the square brackets, so the Wikipedia software creates a link out of the text. External links that have only a URL within brackets, however, are numbered.

Footnotes with a citation template

Creating a freeform footnote, as described in the previous section, is pretty easy, but in articles that contain many footnotes, editors usually use one of Wikipedia's citation templates. Citation templates are big, ugly chunks of text that you'll run across when editing Wikipedia articles, but they have a definite purpose. They organize the internal structure of a footnote by delimiting (that is, defining) each part of the note. It's sort of as if a sentence came with descriptive markings: "This is an introductory phrase. This is the subject of the sentence. This is the verb. This is the object." A citation template defines the parts of a citation—author's name, document title, and so on, by using what Wikipedia calls parameters.

Figure 2-8 shows you three different ways an editor could use a citation template to create the same footnote that you created in the previous section. How an editor uses a template is entirely up to that editor, so you could see any—or all three, mixed together—in a given article. As long as what's displayed is accurate, the templates don't need to be consistent.

Not only can the same citation template look different (Figure 2-8), but there are more than a dozen footnote citation templates. Figure 2-8 shows the cite news template, which is one of the most common. It's designed to cite newspapers, magazines, journals, and periodicals. There are specialized templates for books, Web sites, court cases, and so on. You can see all of these—in a form that makes it easy to copy a template to a Wikipedia article you're editing, by the way—at Wikipedia:Citation templates (shortcut: WP:CITET). (For a quick reference guide with details about the most common templates, go to WP:CITEQR.)

Since you can cite any kind of source using a freeform footnote, as you learned earlier in this chapter, why use standard citations templates at all? There are a number of reasons, some of which you may find compelling:

• A citation template is like a handy form. Just fill it out, and the template takes care of the formatting. When you enter text into a template, you don't have to know what goes first, what goes where, and so on. The template takes care of displaying the citation for the reader.
• Changing the template automatically updates every citation that uses it. For example, if the Wikipedia community decided that the first name of an author should come first, followed by the last name, instead of the current approach, you could change every display of every footnote created with a particular template simply by changing the template itself. This automatic updating is the true power of templates. (But to prevent tampering, high-use templates are protected so that only administrators can change them.)
• Templates may make future automated features possible. Citation templates make it possible (in theory) to do automated searching across articles to find, say, all the referenced articles written by the same author, or all cited articles published on a given date. For that to be valuable, of course, there would need to be many more footnotes in Wikipedia articles—you can help!—and a much higher percentage of citation templates, as opposed to freeform templates.

Multiple footnotes for the same source

If you use the same source to support a number of statements in an article, you don't have to (nor should you) type citation information multiple times. Instead, you use a name= parameter to tell the Wikipedia software that multiple footnotes use the same source. Figure 2-9 shows how it works.

Multiple footnotes are marked up differently than singular ones. The second time that "Source1" is cited in Figure 2-9, it isn't between a pair of tags. Rather, this standalone tag looks like a hybrid: It had the name= part of a starting ref tag, with the slash ("/") of an ending tag (albeit at the end, not the beginning—in XML markup this is called a self-closing tag). When doing multiple footnotes for a single source, the format for all of the footnotes, except the one that actually has citation information in it, goes like this: <ref name="NameYouGiveToTheSource"/>. (For more details on what name to give to a source, see the box about the name= parameter.)

If you forget the ending slash, the software assumes it's a starting tag for a footnote. It then "swallows" all the following text, stopping only when it finds either a closing </ref> tag or gets to the end of the page. That's yet another reason to always preview your changes to an article. If you add one or more footnotes and notice that a chunk of text is no longer visible in the preview, or you have some garish red warning text where the reference link should be, chances are you didn't include a closing slash in one of your <ref> tags or you put the slash in the wrong place.

With what you've learned so far, you now know how to document information in Wikipedia in just about any situation—you can create links, footnotes, and multiple footnotes, and use citation templates. The three techniques described in the rest of this chapter are completely optional. But if you spend a lot of time creating and editing citations, you may find a need for automated citation-creating tools, viewing footnotes for just a section of an article, and adding page numbers to footnotes.

Automated citation tools

When you want to cite a source, you usually have to cut and paste various elements—one by one—from the Web page where you found the source into the edit box where you're assembling the citation. But sometimes, computerized tools can vastly simplify your work: You can simply cut and paste the whole citation, not its individual parts. Here's an assortment of tools to check out:

• Biomedical citation maker by User:Badgettrg. Converts a PubMed ID (PMID), DOI, PMCID, NCT to ((cite journal)), ((cite pmid)), or simple wikiformatting for all journals indexed by PubMed. Bookmarklet is available. Adds links to ACP Journal Club and Evidence-Based Medicine comments if present.
• Citer: Converts a URL, DOI, ISBN, PMID, PMCID, OCLC, or Google Books URL into a citation and shortened footnote. It also can generate citations for certain major news websites (e.g., The New York Times) and the Wayback Machine.
• Citoid: A tool built into both Visual Editor and source editor that attempts to build a full citation based on a URL. See user guide.
• Diberri Template builder: Converts URL, DrugBank ID, HGNC ID, PubMed ID, PubMed Central ID or PubChem ID to full citation.
• MakeRef: A form for creating various ((cite)) templates.
• reFill: Uses Citoid to replace all bare URLs on a Wikipedia page with filled ((cite web)) templates.
• RefScript: A bookmarklet that generates references with a single click. Works with a few news websites (BBC, Daily Mirror, Daily Telegraph, Huffington Post, Huffington Post Canada, New York Times, Washington Post, Boston Globe, Times of India, Financial Times, The Economist, Business Week, Ars Technica, TG Daily) and it can learn any other newspaper or website.
• WebRef: A bookmarklet automating the filling of the ((cite web)) template.
• Wikipedia AutoReferencer, Microsoft word tool to convert embedded links to wikitext
• Wikipedia-References-Creator: A Firefox addon for creation of references (output changeable).
• Citation Bot (more info) – Partial citations must either contain a DOI, PMID, PMC, ISBN, or enough fields to be uniquely found; the bot will also fix formatting errors
• refToolbar (JavaScript) – Allows you to format a reference during editing when you already have all the data
• Scopus search add-on – Find a reference on Scopus, then with one click it's formatted ready for use in an article

Adding page numbers to footnote numbers

If you're using a book as a source, you may cite information from multiple locations within the book. If so, creating footnotes can be a challenge, because you seem to have three choices:

• You can create a separate citation for every page, leading to a lot of almost-duplicate entries in the "References" section. They'd be identical except for the page number cited.
• You can create a single citation with multiple occurrences, using the name= parameter as discussed in the section about the name= parameter. You can then list, in that one citation, all the pages numbers where you got information. (It's better than omitting the page numbers, though not by much.)
• You can use Harvard-style footnotes (see the section about styles of footnotes) instead of regular footnotes. (But you may be out of luck if the article already has a significant number of regular footnotes, because other editors may object to mixing the two styles.)

Fortunately, there's a fourth option, using a citation template called Rp. It lets you slot in the page number right next to the footnote number, where your readers can readily see it. Figure 2-10 shows how it works.