Sources, to be acceptable for use on Wikipedia, must meet all of the following criteria:

1. Publication. The information must be published; that is, it must be fixed, transcribed, or recorded in some medium which is both persistent and which is available to be read or inspected, without restrictions on disclosure. Persistent electronic media are acceptable. Ephemera are generally not acceptable (unless archived and published); nor are documents or artifacts which are secrets, only available under nondisclosure, or otherwise cannot be verified by the general public. It is not a requirement that sources be available for no cost, or not be subject to copyright or other restrictions on reproduction. Publication, in this context, is not limited to works which are printed and/or distributed by a major publishing house.
2. Traceability to author(s). Sources which are wholly anonymous are not acceptable, even in support of a weasel-word claim (which should be avoided anyway). Exceptions exist for anonymous sources when interviewed or studied by a reliable source who vouches for the anonymous source, such as Deep Throat prior to his identity being disclosed; as well as for surveys and such where the individual participants are unknown, but the statistical aggregate is published. Pseudonymous source may be acceptable, especially if a person is well-known by a pseudonym; however pseudonymous sources may pose additional difficulties with the next requirement.
3. Authenticity. Sources must have some evidence of authenticity; we must be reasonably sure that sources are not forgeries or misrepresentations. Authenticity can be demonstrated in several ways:

   • The source is given in a reputable publication in a matter which vouches for its authenticity
   • The source is certified by an authority or official finding
   • The source is self-published, or the purported authors themselves vouch for the source's authenticity in a reputable source
   • The source is corroborated by witnesses who go on record.
   • A difficult-to-forge recording exists of the author(s) making the statements or claims in question.

   Some evidence of authenticity is required for a source to be acceptable; anonymous hearsay is never acceptable. Sources which are explicitly disavowed by the purported author(s) should be treated with extra caution, and should not be used unless there is strong evidence that the source is indeed genuine. Note that this requirement should not be construed to mean that every source must be notarized--if there is no reasonable doubt to a source's authenticity, then a minimal demonstration is acceptable. Some demonstration of authenticity must be provided however; it is not acceptable to include words attributed to George W. Bush by your neighbor's uncle and not vouched for elsewhere.

4. Relevance. Sources must be relevant--there must be some reason for the reader to care about what the author has to say. For example, the opinion of a random individual on the presidency of George W. Bush, as published in a letter to the editor of a major newspaper, is not relevant; and thus should not be included--even though it is published, traceable to its author, and given in a reputable publication. Relevance can be imputed several ways--through explicit personal knowledge, through subject-matter authority, through general notability of the author, through demonstrable correlation with the opinion(s) of a large group of people, etc.

Note that this policy is the minimum standard for inclusion as a reference in Wikipedia. Sources may meet this standard and still not be authoritative, reliable, accurate, free from bias, or undisputed. Sources which meet this minimum standard but which fail to meet stricter standards may be used, but should be used with caution. In particular, such sources should be explicitly attributed to their author(s) or publisher(s) in an article's prose (rather than being presented as fact with the author only given in the notes), and disputes considering the source's veracity should be described.

Sources which fail to meet this standard may be cited (with caution) in the "External links" or "For further reading" sections of an article; but may not be used to directly buttress an article's claims.