"The library was still giving trouble; a few books in some of the more obscure corners of the stacks retained some autonomy, dating back to an infamous early experiment with flying books, and lately they'd begun to breed. Shocked undergraduates had stumbled on books in the very act.
Which sounded interesting, but so far the resulting offspring had either been predictably derivative (in fiction) or stunningly boring (non-fiction); hybrid pairings between fiction and non-fiction were the most vital."
The Magician's Land - Lev Grossman

The Magician's Land by Lev Grossman