Here is a nice large collection of all non-fiction books that is just over 600GB. Please seed if you can!

magnet:?xt=urn:btih:1488b5d9185940734c6c0a316aa1187ec1e945ea&dn=PDFs%2band%2beBooks.rar&tr=udp%3a%2f%2ftracker.open-internet.nl%3a6969%2fannounce&tr=udp%3a%2f%2ftracker.coppersurfer.tk%3a6969%2fannounce