One of the most important distinctions we need to make when writing for the Web is the difference between how texts are related and how subjects are related. If that sentence made you say “Huh?”, let me explain.
In the book world, the principal reason for one book to refer to another book or article was for purposes of citation. A citation says, for support for this claim, see this work. The citation is used either to prove an assertion about another text, or to support an assertion about a subject with reference to an authoritative text. Any old text on the subject won’t do. It is the authority of the specific cited text that is being invoked.