My own unwritten short stories reminded me of the Invisible Library:
The Invisible Library is a collection of books that only appear in other books. Within the library’s catalog you will find imaginary books, pseudobiblia, artifictions, fabled tomes, libris phantastica, and all manner of books unwritten, unread, unpublished, and unfound.
There’s a very funny essay called Books Within Books by Max Beerbohm on that site:
In some three-volume novel that I once read at a seaside place, having borrowed it from the little circulating library, there was a young poet whose sudden leap into the front rank has always laid a special hold on my imagination. The name of the novel itself I cannot recall; but I remember the name of the young poetâ€”Aylmer Deane; and the forever unforgettable title of his book of verse was POMENTS: BEING POEMS OF THE MOOD AND THE MOMENT. What would I not give to possess a copy of that work?