Wikipedia:ATTREQ

The CC BY-SA, section 4(c), states that:

You must ... provide ... the name of the Original Author (or pseudonym, if applicable) ... and ... in the case of an Adaptation, a credit identifying the use of the Work in the Adaptation (e.g., "French translation of the Work by Original Author," or "Screenplay based on original Work by Original Author"). The credit required by this Section 4(c) may be implemented in any reasonable manner; provided, however, that in the case of a Adaptation or Collection, at a minimum such credit will appear, if a credit for all contributing authors of the Adaptation or Collection appears, then as part of these credits and in a manner at least as prominent as the credits for the other contributing authors.

The GFDL, section 4-I, states that:

... you must ... Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page.

in any of the following fashions: a) through a hyperlink (where possible) or URL to the article or articles you contributed to, b) through a hyperlink (where possible) or URL to an alternative, stable online copy which is freely accessible, which conforms with the license, and which provides credit to the authors in a manner equivalent to the credit given on this website, or c) through a list of all authors. (Any list of authors may be filtered to exclude very small or irrelevant contributions.)

If material is used without attribution, it violates the licensing terms under which it has been provided, which in turn violates the Reusers' rights and obligations clause of .

The correct attribution of text copied from one article to another allows editors to find easily the previous edit history of the copied text with all the advantages that access to the edit history of text contained in an article provides. Listed below are some advantages appropriate attribution brings that are specific to text copied from one article to another.

If text with one or more short citations is copied from one or more parent articles into a child article, but the corresponding full reference in the parent's references section are not copied across, without appropriate attribution as specified below, it can be difficult to identify the full reference needed to support the short citations (see here for an example).

However, attributing the first two is encouraged.

It may sometimes be necessary to delete specific parts of an article's history for various reasons (copyright violations introduced but later excised; extreme personal attacks; personal information) through Selective History deletion, Revision Deletion or Oversight. If the article retains contributions placed by users in the deleted / oversighted revisions, those must be attributed. Dummy edits should be used for this purpose, whenever practical; otherwise, talk page attribution will be necessary. A typical dummy edit summary could read, for instance Revision deletion for reason XYZ: Article was started by and retains contributions from [[User:Example]], as well as contributions from [[User:Example2]] and [[User:Example3]]

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