I'm looking for a book that's a collection of encyclopedia-style entries about books that were lost/forgotten/alternate versions/never actually written. These weren't REAL lost books, they were parodies written by the author poking fun at various classics and literary trends, from ancient history to modern times. I wish I could remember some examples, but it's been a good 20 years since I've read it; I do recall some famous sci-fi works were parodied.
The book was in English and probably published in the early 90's. My copy was a paperback a little larger and thinner than a mass market paperback, the cover was light tan and mostly text with either small or no illustration.