This is a pretty fun list: pretend books mentioned in real books. It’s designed as a “library,” so (rather inconveniently) organized by imaginary author, alphabetically (personally, I’d prefer to have them listed by the real book in which they are included).
It looks like the curator of this rather impressive and oddball list hasn’t read Neil Gaiman’s Sandman comic books, which is a pity. Sandman has a whole library of pretend books, the premise being it’s a collection of all the books the authors dreamed of writing but never actually got around to. It’s a fascinating list, and shows an interesting peek at sigh authors’ (imagined) psyches.
Still, take a moment and peruse the books that only exist as a figment of someone else’s imagination. It’s sort of fun.