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Wikipedia articles should be based on "reliable, published sources, making sure that all majority and significant minority views that have appeared in those sources are covered (see "Wikipedia:Neutral point of view). If no reliable sources can be found on a topic, "Wikipedia should not have an article on it.

The guideline in this page discusses the reliability of various types of sources. The policy on sourcing is "Wikipedia:Verifiability, which requires "inline citations for any material challenged or likely to be challenged, and for all quotations. The policy is strictly applied to all material in the mainspace—articles, lists, and sections of articles—without exception, and in particular to "biographies of living persons, which states:

Contentious material about living persons (or, "in some cases, recently deceased) that is unsourced or poorly sourced—whether the material is negative, positive, neutral, or just questionable—should be removed immediately and without waiting for discussion.

In the event of a contradiction between this guideline and our policies regarding sourcing and attribution, the policies take priority and editors should seek to resolve the discrepancy. 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.



Source reliability falls on a spectrum: highly reliable sources, clearly unreliable sources, and many in the middle. Editors must use their judgment to draw the line between usable and unreliable sources.

Articles should be based on reliable, "third-party, published sources with a reputation for fact-checking and accuracy. This means that we publish the opinions only of reliable authors, and not the opinions of Wikipedians who have read and interpreted primary source material for themselves. The following 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.

Definition of a source[edit]

The word "source" when citing sources on Wikipedia has three related meanings:

Any of the three can affect reliability. Reliable sources may be published materials with a reliable publication process, authors who are regarded as authoritative in relation to the subject, or both. These qualifications should be demonstrable to other people.

Definition of published[edit]


The term ""published" is most commonly associated with text materials, either in traditional printed format or online. However, audio, video, and multimedia materials that have been recorded then broadcast, distributed, or archived by a reputable party may also meet the necessary criteria to be considered reliable sources. 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 convenient, but by no means necessary, for the archived copy to be accessible via the Internet.

Context matters[edit]


The reliability of a source depends on context. Each source must be carefully weighed to judge whether it is reliable for the statement being made in the Wikipedia article and is an appropriate source for that content. In general, the more people engaged in checking facts, analyzing legal issues, and scrutinizing the writing, the more reliable the publication. Information provided in passing by an otherwise reliable source that is not related to the principal topics of the publication may not be reliable; editors should cite sources focused on the topic at hand where possible. Sources should directly support the information as it is presented in the Wikipedia article.

Age matters[edit]


Especially in scientific and academic fields, older sources may be inaccurate because new information has been brought to light, new theories proposed, or vocabulary changed. In areas like politics or fashion, laws or trends may make older claims incorrect. Be sure to check that older sources have not been superseded, especially if it is likely the new discoveries or developments have occurred in the last few years. In particular, "newer sources are generally preferred in medicine.

Sometimes sources are too new to use, such as with "breaking news (where later reports might be more accurate), and primary sources which purport to debunk a long-standing consensus or introduce a new discovery (in which case awaiting studies that attempt to replicate the discovery might be a good idea, or reviews that validate the methods used to make the discovery).

With regard to historical events, older reports (closer to the event, but not too close such that they are prone to the errors of breaking news) tend to have the most detail, and are less likely to have errors introduced by repeated copying and summarizing. However, newer secondary and tertiary sources may have done a better job of collecting more reports from primary sources and resolving conflicts, applying modern knowledge to correctly explain things that older sources could not have, or remaining free of bias that might affect sources written while any conflicts described were still active or strongly felt.

Sources of any age may be prone to "recentism, and this needs to be balanced out by careful editing.

Some types of sources[edit]


Many Wikipedia articles rely on scholarly material. When available, academic and peer-reviewed publications, scholarly monographs, and textbooks are usually the most reliable sources. However, some scholarly material may be outdated, in competition with alternative theories, or controversial within the relevant field. Try to cite current scholarly consensus when available, recognizing that this is often absent. 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.



News organizations[edit]


News sources often contain both factual content and opinion content. "News reporting" from well-established news outlets is generally considered to be reliable for statements of fact (though even the most reputable reporting sometimes contains errors). News reporting from less-established outlets is generally considered less reliable for statements of fact. Most newspapers also reprint items from "news agencies such as "BBC News, "Reuters, "Interfax, "Agence France-Presse, "United Press International or the "Associated Press, which are responsible for accuracy. The agency should be cited in addition to the newspaper that reprinted it.

Editorial commentary, analysis and "opinion pieces, whether written by the editors of the publication ("editorials) or outside authors ("op-eds) are reliable primary sources for "statements attributed to that editor or author, but are rarely reliable for statements of fact. "Human interest reporting is generally not as reliable as news reporting, and may not be subject to the same rigorous standards of fact-checking and accuracy (see "junk food news).[6]

Vendor and e-commerce sources[edit]

Although the content guidelines for "external links prohibits linking to "Individual web pages that primarily exist to sell products or services," inline citations may be allowed to e-commerce pages such as that of a book on a bookseller's page or an album on its streaming-music page, in order to "verify such things as titles and running times. Journalistic and academic sources are preferable, however, and e-commerce links should be replaced with non-commercial reliable sources if available.

Rankings proposed by vendors (such as bestseller lists at Amazon) usually have at least one of the following problems:

  1. It may be impossible to provide a stable source for the alleged ranking;
  2. When only self-published by the vendor, i.e. no reliable third-party source confirming the ranking as being relevant, the ranking would usually carry insufficient weight to be mentioned in any article.

For such reasons such rankings are usually avoided as Wikipedia content.

Biased or opinionated sources[edit]


Wikipedia articles are required to present a "neutral point of view. However, reliable sources are not required to be neutral, unbiased, or objective. Sometimes non-neutral sources are the best possible sources for supporting information about the different viewpoints held on a subject.

Common sources of bias include political, financial, religious, philosophical, or other beliefs. Although a source may be biased, it may be reliable in the specific context. When dealing with a potentially biased source, editors should consider whether the source meets the normal requirements for reliable sources, such as editorial control and a reputation for fact-checking. Editors should also consider whether the bias makes it appropriate to use "in-text attribution to the source, as in "Feminist "Betty Friedan wrote that..."; "According to the Marxist economist "Harry Magdoff..."; or "Conservative Republican presidential candidate "Barry Goldwater believed that...".

Questionable and self-published sources[edit]

Questionable sources[edit]


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, that are promotional in nature, or that rely heavily on rumors and personal opinions.[9] Questionable sources are generally unsuitable for citing contentious claims about third parties, which includes claims against institutions, persons living or dead, as well as more ill-defined entities. The proper uses of a questionable source are very limited.

Beware of sources that sound reliable but do not have the "reputation for fact-checking and accuracy that WP:RS requires.[10] The Journal of 100% Reliable Factual Information might have a reputation for ""predatory" behavior, which includes questionable business practices and/or peer-review processes that raise concerns about the reliability of their journal articles.[11][12]

Self-published sources (online and paper)[edit]


Anyone can create a "personal web page or "publish their own book and claim to be an expert in a certain field. For that reason, self-published media are largely not acceptable. Self-published books and newsletters, personal pages on social networking sites, "tweets, and posts on "Internet forums are all examples of self-published media.

User-generated content[edit]


Content from websites whose content is largely user-generated is also generally unacceptable. Sites with user-generated content include personal websites, personal blogs, group blogs, "internet forums, the "Internet Movie Database (IMDb), "Ancestry.com, "content farms, most "wikis including "Wikipedia, and other collaboratively created websites. In particular, a "wikilink is not a reliable source.


Content from a collaboratively created website may be acceptable if the content was authored by, and is credited to, credentialed members of the site's editorial staff.

Some news outlets host interactive columns that they call "blogs", and these may be acceptable as sources if the writers are professional journalists or professionals in the field on which they write, and the blog is subject to the news outlet's full editorial control. Posts left by readers may never be used as sources (see "WP:Verifiability § Newspaper and magazine blogs).

Self-published material may sometimes be acceptable when its author is an established expert whose work in the relevant field has been published by reliable "third-party publications. Such material, although written by an established author, likely lacks the fact checking that publishers provide. Avoid using them to source "extraordinary claims. Self-published information should never be used as a third-party source about another living person, even if the author is a well-known professional researcher or writer (see "WP:Biographies of living persons § Reliable sources).

Self-published and questionable sources as sources on themselves[edit]


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 the following criteria are met:

These requirements also apply to pages from social networking websites such as "Twitter, "Tumblr, and "Facebook.

Reliability in specific contexts[edit]

Biographies of living persons[edit]

Editors must take particular care when writing biographical material about living persons. Contentious material about a living person that is unsourced or poorly sourced should be removed immediately; 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[edit]


Wikipedia articles should be based mainly on reliable "secondary sources, i.e., a document or recording that relates or discusses information originally presented elsewhere.

Reputable "tertiary sources, such as introductory-level university textbooks, almanacs, and encyclopedias, may be cited. However, although Wikipedia articles are tertiary sources, Wikipedia employs no systematic mechanism for fact checking or accuracy. Thus, Wikipedia articles (and Wikipedia mirrors) in themselves are not reliable sources for any purpose (except as sources on themselves per "WP:SELFSOURCE). Because Wikipedia forbids original research, there is nothing reliable in it that is not citable with something else.

"Primary sources are often difficult to use appropriately. Although they can be both reliable and useful in certain situations, they must be used with caution in order to avoid "original research. Although specific facts may be taken from primary sources, secondary sources that present the same material are preferred. Large blocks of material based purely on primary sources should be avoided. All interpretive claims, analyses, or synthetic claims about primary sources must be referenced to a secondary source, rather than original analysis of the primary-source material by Wikipedia editors.

When editing articles and the use of primary sources is a concern, in-line templates, such as {{"primary source-inline}} and {{"better source}}, or article templates, such as {{"primary sources}} and {{"refimprove science}}, may be used to mark areas of concern.

Medical claims[edit]


Ideal sources for biomedical assertions include "general or "systematic reviews in reliable, third-party, published sources, such as reputable "medical journals, widely recognised standard textbooks written by experts in a field, or "medical guidelines and position statements from nationally or internationally reputable expert bodies. It is vital that the biomedical information in all types of articles be based on reliable, third-party, published sources and accurately reflect current medical knowledge.


The accuracy of quoted material is paramount and the accuracy of quotations from living persons is especially sensitive. To ensure accuracy, the text of quoted material is best taken from (and cited to) the original source being quoted. If this is not possible, then the text may be taken from a reliable secondary source (ideally one that includes a citation to the original). No matter where you take the quoted text from, it is important to "make clear the actual source of the text, as it appears in the article.

Partisan secondary sources should be viewed with suspicion as they may misquote or quote out of context. In such cases, look for neutral corroboration from another source.

Any analysis or interpretation of the quoted material, however, should rely on a secondary source (See: "WP:No original research).

Academic consensus[edit]


A statement that all or most scientists or scholars hold a certain view requires reliable sourcing that directly says that all or most scientists or scholars hold that view. Otherwise, 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. Stated simply, any statement in Wikipedia that academic consensus exists on a topic must be sourced rather than being based on the opinion or assessment of editors. "Review articles, especially those printed in academic review journals that survey the literature, can help clarify academic consensus.

Usage by other sources[edit]


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, whereas 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[edit]


Some sources may be considered reliable for statements as to their author's opinion, but not for statements asserted as fact. For example, an inline qualifier might say "[Author XYZ] says....". A prime example of this is "opinion pieces in sources recognized as reliable. When using them, it is best to clearly attribute the opinions in the text to the author and make it clear to the reader that they are reading an opinion.

Otherwise reliable news sources—for example, the website of a major news organization—that publish in a blog-style format for some or all of their content may be as reliable as if published in a more "traditional" 20th-century format.

There is an important exception to sourcing statements of fact or 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#Reliable sources and "WP:BLP#Using the subject as a self-published source.

Breaking news[edit]


Breaking news reports often contain serious inaccuracies. As an electronic publication, Wikipedia can and should be up to date, but "Wikipedia is not a newspaper and it does not need to go into all details of a current event in real time. It is better to wait a day or two after an event before adding details to the encyclopedia, than to help spread potentially false rumors. This gives journalists time to collect more information and verify claims, and for investigative authorities to make official announcements. The "On the Media Breaking News Consumer's Handbook contains several suggestions to avoid unreliable information, such as distrusting anonymous sources, distrusting unconfirmed reports and those attributed to other news media, seeking multiple sources, seeking eyewitness reports, being wary of potential hoaxes, and being skeptical of reports of possible additional attackers in mass shootings.

Claims sourced to initial news reports should be replaced with better-researched ones as soon as possible, especially where incorrect information was imprudently added. All breaking news stories, without exception, are primary sources, and must be treated with caution per "WP:PSTS.

When editing articles covering current events, also keep in mind the essay on "recentism bias.

{{"current}}, {{"recent death}}, or other "current event-related templates may be added to the top of articles concerning breaking news, to alert readers that some information may be inaccurate, and to draw attention to the need to add improved sources as they become available. Keep in mind, however, that these current event-related templates are not intended to be used to mark an article that merely has recent news articles about the topic; if it were, hundreds of thousands of articles would have this template, with no informational consequence (see also "Wikipedia:No disclaimers in articles).

See also[edit]


"Wikipedia:Template messages/Cleanup/Verifiability and sources lists many templates, including

Policies and guidelines
Locating reliable sources


  1. ^ Examples include The Creation Research Society Quarterly and Journal of Frontier Science (the latter uses blog comments as peer review).
  2. ^ Please keep in mind that any exceptional claim would require "exceptional sources, and this is policy.
  3. ^ A variety of these incidents have been documented by "Private Eye and others and discussed on Wikipedia, where incorrect details from articles added as "vandalism or otherwise have appeared in newspapers


  1. ^ "Beall, Jeffrey (December 1, 2012). "Criteria for Determining Predatory Open-Access Publishers" (2nd ed.). Scholarly Open Access. 
  2. ^ "Kolata, Gina (April 7, 2013). "Scientific Articles Accepted (Personal Checks, Too)". The New York Times. Retrieved April 11, 2013. 
  3. ^ Butler, Declan (March 28, 2013). "Sham journals scam authors: Con artists are stealing the identities of real journals to cheat scientists out of publishing fees". Nature. 495. pp. 421–422. Retrieved April 11, 2013. 
  4. ^ "Bohannon, John (4 October 2013). "Who's afraid of peer review?". Science. 342 (6154): 60–65. "doi:10.1126/science.342.6154.60. 
  5. ^ Kolata, Gina (30 October 2017). "Many Academics Are Eager to Publish in Worthless Journals". Retrieved 2 November 2017 – via www.nytimes.com. 
  6. ^ Miller, Laura (October 16, 2011). "'Sybil Exposed': Memory, lies and therapy". "Salon. Salon Media Group. Retrieved October 17, 2011. [Debbie Nathan] also documents a connection between Schreiber and Terry Morris, a 'pioneer' of this [human interest] genre who freely admitted to taking 'considerable license with the facts that are given to me.' 
  7. ^ "Book reviews". Scholarly definition document. Princeton. 2011. Retrieved September 22, 2011. 
  8. ^ "Book reviews". Scholarly definition document. Virginia Polytechnic Institute and State University. 2011. Retrieved September 22, 2011. 
  9. ^ Malone Kircher, Madison (November 15, 2016). "Fake Facebook news sites to avoid". New York Magazine. Retrieved November 15, 2016. 
  10. ^ An example is the "Daily Mail, which is broadly considered a questionable and prohibited source, per "this RfC.
  11. ^ "Beall, Jeffrey (25 February 2015). "'Predatory' Open-Access Scholarly Publishers" (PDF). "The Charleston Advisor. 
  12. ^ "Beall, Jeffrey. "Potential, possible, or probable predatory scholarly open-access publishers". Retrieved 23 July 2013. 

External links[edit]

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