One thing to keep in mind is that Project Xanadu predates the web by a decade or so. Whereas the web settled on simple unidirectional links embedded in linear text documents, Ted Nelson's Xanadu was aiming for bidirectional transclusion and nonlinear documents ("zippered lists").

Reading old papers from Nelson, Engelbart, or Bush is a lot of fun, though it can sometimes take a little work to get into a pre-internet headspace. I don't read very many authors these days who are attempting to rethink fundamental computer interface concepts like that, though there are a few.