Most documents are linked regarding the topic. If you go on a math page, you've got math links. Ancient and holy texts could be referenced in multiple ways, because it could be interpreted in multiple ways (or the correct way is unknown), but not something like guides. If a guide is written in more than one meaning, it is not a good guide. Learning should be more seen like a tree, you go down the route of branches and specialize more in the directions of it and the branches lead the references. At the beginning you learn the language, later you know it, otherwise every word needs to be linked.