This page documents an English Wikipedia content guideline. 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.

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To obtain or provide community input on whether a source meets our reliability standards for a particular use, see the reliable sources noticeboard.

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List of policies and guidelines

This guideline discusses the reliability of various types of sources. The policy on sourcing is Wikipedia:Verifiability. Where there is a conflict between this page and the policy, the policy takes precedence, and this page should be changed to reflect the content of the policy.

Wikipedia articles should rely on reliable, published sources, making sure that all majority and significant-minority views that have appeared in reliable, published sources are covered; see Wikipedia:Neutral point of view. The word "source" as used on Wikipedia has three related meanings: the piece of work itself (the article, paper, document, book), the creator of the work (for example, the writer), and the publisher of the work (for example, The New York Times or Cambridge University Press). All three can affect reliability. Reliable sources may therefore be published materials with a reliable publication process; they may be authors who are regarded as authoritative in relation to the subject in question; or they may be both.

How reliable a source is, and the basis of its reliability, depends on the context. As a rule of thumb, the more people engaged in checking facts, analyzing legal issues, and scrutinizing the writing, the more reliable the publication. Sources should directly support the information as it is presented in an article, and should be appropriate to the claims made. If a topic has no reliable sources, Wikipedia should not have an article on it.

Other policies relevant to sourcing are Wikipedia:No original research and Wikipedia:Biographies of living persons. For questions about the reliability of particular sources, see Wikipedia:Reliable sources/Noticeboard.

Contents 1 Overview 2 Types of sources 2.1 Scholarship 2.2 News organizations 3 Self-published and questionable sources 3.1 Questionable sources 3.2 Self-published sources (online and paper) 3.3 Self-published and questionable sources as sources on themselves 4 Reliability in specific contexts 4.1 Biographies of living persons 4.2 Primary, secondary, and tertiary sources 4.3 Quotations 4.4 Academic consensus 4.5 Usage by other sources 4.6 Statements of opinion 4.7 Other examples 5 Notes 6 See also 7 External links

Overview

Articles should rely on reliable, third-party, published sources with a reputation for fact-checking and accuracy. This means that we only publish the opinions of reliable authors, and not the opinions of Wikipedians who have read and interpreted primary source material for themselves. The following specific examples cover only some of the possible types of reliable sources and source reliability issues, and are not intended to be exhaustive. Proper sourcing always depends on context; common sense and editorial judgment are an indispensable part of the process.

The term "published" is most commonly associated with text materials. However, audio, video, and multimedia materials that have been recorded then broadcast, distributed, or archived by a reputable third-party may also meet the necessary criteria to be considered reliable source. Like text sources, media sources must be produced by a reliable third-party and be properly cited. Additionally, an archived copy of the media must exist. It is useful but by no means necessary for the archived copy to be accessible via the internet.

Types of sources

Many Wikipedia articles rely on scholarly material. Academic and peer-reviewed publications are usually the most reliable sources when available. However, some scholarly material may be outdated, superseded by more recent research, in competition with alternate theories, or controversial within the relevant field. Try to cite scholarly consensus when available. Reliable non-academic sources may also be used in articles about scholarly issues, particularly material from high-quality mainstream publications. Deciding which sources are appropriate depends on context. Material should be attributed in-text where sources disagree.

Scholarship

• Articles should rely on secondary sources whenever possible. Wikipedians should not rely on, or try to interpret the content or importance of, primary sources. See Wikipedia:No original research.
• Material that has been vetted by the scholarly community is regarded as reliable; this means published in reputable peer-reviewed sources or by well-regarded academic presses.
• Finished Ph.D. dissertations, which are publicly available, are considered publications by scholars and are routinely cited in footnotes. They have been vetted by the scholarly community; most are available via interlibrary loan. UMI has published two million dissertations since 1940. Dissertations in progress are not vetted and are not regarded as published. They are not reliable sources as a rule.
• The scholarly acceptance of a source can be verified by confirming that the source has entered mainstream academic discourse, for example by checking the number of scholarly citations it has received in citation indexes. A corollary is that journals not included in a citation index, especially in fields well covered by such indexes, should be used with caution, though whether it is appropriate to use will depend on the context.
• Isolated studies are usually considered tentative and may change in the light of further academic research. The reliability of a single study depends on the field. Studies relating to complex and abstruse fields, such as medicine, are less definitive. Avoid undue weight when using single studies in such fields. Meta-analyses, textbooks, and scholarly review articles are preferred when available, so as to provide proper context.

News organizations

Material from mainstream news organizations is welcomed, particularly the high-quality end of the market.

• For information about academic topics, both scholarly sources and high-quality non-scholarly sources are acceptable, depending on context.
• While the reporting of rumors has a news value, Wikipedia is an encyclopedia and should only include information verified by reliable sources. Wikipedia is not the place for passing along gossip and rumors.
• Some news organizations have used Wikipedia articles as the sole source for their work. Editors should therefore beware of circular sourcing.^[1]

Self-published and questionable sources

Questionable sources

Questionable sources are those with a poor reputation for checking the facts, or with no editorial oversight. Such sources include websites and publications expressing views that are widely acknowledged as extremist, or promotional in nature, or which rely heavily on rumors and personal opinions. Questionable sources should only be used as sources of material on themselves, especially in articles about themselves. Questionable sources are generally unsuitable as a basis for citing contentious claims about third parties.

Self-published sources (online and paper)

Anyone can create a website or pay to have a book published, then claim to be an expert in a certain field. For that reason self-published media—whether books, newsletters, personal websites, open wikis, blogs, Internet forum postings, or tweets—are largely not acceptable.

"Blogs" in this context refers to personal and group blogs. Some newspapers host interactive columns that they call blogs, and these may be acceptable as sources so long as the writers are professionals and the blog is subject to the newspaper's full editorial control. Posts left by readers may never be used as sources.

Self-published material may, in some circumstances, be acceptable when produced by an established expert on the topic of the article whose work in the relevant field has previously been published by reliable third-party publications. Self-published sources should never be used as third-party sources about living persons, even if the author is a well-known professional researcher or writer; see WP:BLP#Reliable sources.

Self-published and questionable sources as sources on themselves

Self-published or questionable sources may be used as sources of information about themselves, especially in articles about themselves, without the requirement that they be published experts in the field, so long as:

1. the material is not unduly self-serving;
2. it does not involve claims about third parties;
3. it does not involve claims about events not directly related to the subject;
4. there is no reasonable doubt as to its authenticity;
5. the article is not based primarily on such sources.

Reliability in specific contexts

Biographies of living persons

Editors must take particular care when writing biographical material about living persons, for legal reasons and in order to be fair. Remove unsourced or poorly sourced contentious material immediately if it is about a living person, and do not move it to the talk page. This applies to any material related to living persons on any page in any namespace, not just article space.

Primary, secondary, and tertiary sources

Wikipedia articles should be based on reliable secondary sources. This means that while primary or tertiary sources can be used to support specific statements, the bulk of the article should rely on secondary sources.

Tertiary sources such as compendia, encyclopedias, textbooks, and other summarizing sources may be used to give overviews or summaries, but should not be used in place of secondary sources for detailed discussion. Wikipedia itself, although a tertiary source, should not be used as a source within articles, nor should any mirrors or forks of Wikipedia be accepted as reliable sources for any purpose.

Primary sources, on the other hand, are often difficult to use appropriately. While they can be reliable in many situations, they must be used with caution in order to avoid original research.

Quotations

The accuracy of quoted material is paramount; the accuracy of quotations from living persons is especially sensitive. Quotations should be cited to the original source if possible; when secondary sources are used, those that cite the original source should be preferred over those that don't. Partisan secondary sources should be viewed with suspicion if they lack neutral corroboration.

It is important to make clear the actual source of the text as it appears in the article.

Academic consensus

The statement that all or most scientists or scholars hold a certain view requires reliable sourcing. Without a reliable source that claims a consensus exists, individual opinions should be identified as those of particular, named sources. Editors should avoid original research especially with regard to making blanket statements based on novel syntheses of disparate material. The reliable source needs to claim there is a consensus, rather than the Wikipedia editor. For example, even if every scholarly reliable source located states that the sky is blue, it would be improper synthesis to write that there is a scientific consensus that the sky is blue, unless sources cited also make such a claim.

Usage by other sources

How accepted, high-quality reliable sources use a given source provides evidence, positive or negative, for its reliability and reputation. The more widespread and consistent this use is, the stronger the evidence. For example, widespread citation without comment for facts is evidence of a source's reputation and reliability for similar facts, while widespread doubts about reliability weigh against it. If outside citation is the main indicator of reliability, particular care should be taken to adhere to other guidelines and policies, and to not represent unduly contentious or minority claims. The goal is to reflect established views of sources as far as we can determine them.

Statements of opinion

Some sources may be considered reliable for statements as to their author's opinion, but not for statements of fact. A prime example of this are Op-ed columns that are published in mainstream newspapers. When discussing what is said in such sources, it is important to directly attribute the material to its author, and to do so in the main text of the Wikipedia article so readers know that we are discussing someone's opinion.

There is, however, an important exception to sourcing statements of opinion: Never use self-published books, zines, websites, webforums, blogs and tweets as a source for material about a living person, unless written or published by the subject of the biographical material. "Self-published blogs" in this context refers to personal and group blogs (see: WP:BLP#Sources and WP:BLP#Using the subject as a self-published source).

Note that otherwise reliable news sources--for example, the website of a major news organization--that happens to publish in a "blog" style format for some or all of its content may be considered to be equally reliable as if it were published in a more "traditional" 20th-century format of a classic news story. However, the distinction between "opinion pieces" and news should be considered carefully.

Other examples

See Wikipedia:Reliable source examples for examples of the use of statistical data, advice by subject area (including history, physical sciences, mathematics and medicine, law, business and commerce, popular culture and fiction), and the use of electronic or online sources.

Notes

See also

• {{fact}} or {{cn}} – adds: ^{[citation needed]}
• {{vc}} or {{rs}} – adds: ^{[unreliable source?]}
• Wikipedia:Citing sources
• Wikipedia:Common knowledge – essay
• Wikipedia:Current science and technology sources
• Wikipedia:Fringe theories
• Wikipedia:Independent sources – essay
• Wikipedia:Offline sources – essay
• Wikipedia:News sources
• Wikipedia:No original research
• Wikipedia:Reliable sources (medicine-related articles)
• Wikipedia:Reliable sources/Flaws – essay
• Wikipedia:Reliable sources/Noticeboard – obtain community input on whether or not a source meets our reliability standards for a particular use
• Wikipedia:Wikipedia clones – essay
• Wikipedia:Wikipedia Signpost/2008-06-26/Dispatches – Signpost article
• Wikipedia:WikiProject Fact and Reference Check

External links

• How to Read a Primary Source, Reading, Writing, and Researching for History: A Guide for College Students, Patrick Rael, 2004.
• How to Read a Secondary Source, Reading, Writing, and Researching for History: A Guide for College Students, Patrick Rael, 2004.