Source. The book or web page being used as the source. For books, include author, title, publisher, page number, etc. For online source, please link to it. For example: [http://www.website.com/webpage.html].
Article. The Wikipedia article(s) in which it is being used. For example: [[Article name]].
Content. The exact statement(s) in the article that the source is supporting. Please supply a WP:DIFF or put the content inside block quotes. For example: <blockquote>text</blockquote>. Many sources are reliable for statement "X" but unreliable for statement "Y".
While we attempt to offer a second opinion, and the consensus of several editors can generally be relied upon, answers are not official policy.