Secretly Public Domain: Most books published in the US before 1964
I would be very surprised if this were true. I volunteer with standardebooks.org on getting books in the public domain transcribed, proofread, and typeset for modern e-readers. There are a swarm of books that we would like to upload but can't, due to unclear copyright status on them. This includes stuff that everyone and their mother has probably bought several times already, including the works of HP Lovecraft, Robert E. Howard, etc. For most of these, we still follow the Mickey Mouse rule, and do not proceed until we are absolutely sure they're safe.Case in point, I've been thinking about transcribing The Worm Ouroboros[0] for some time, as it should be in the public domain even by conservative estimates, and yet I can't formally verify its copyright status, so I haven't yet.[0] https://en.wikipedia.org/wiki/The_Worm_Ouroboros