Pseudobiblion

A pseudobiblion (from Italian: "fictional book", pl. pseudobiblium; compare pseudoliber, pseudolibri) is a book or any type of written work that is referenced within a narrative of any medium, but which has no original existence outside the referencing narrative. The grimoire Necronomicon, as described, quoted, or paraphrased by H. P. Lovecraft and other writers of weird fiction, may be considered as an example of such a pseudobiblion.