The Harvard Langdell Law Library, the Countway Library of Medicine, and the Houghton Collection all found at least one book bound in man flesh. One book contained an inscription from around 1632 that plainly states how the covering of the book is the flesh of one of the writers friends, taken after the man was flayed alive.
A big part of me really wants this to be untrue, just because it would make this world not such a creepy and strange a place as it is in my mind. Just wow. I have no words.