https://open.umn.edu/opentextbooks/ https://freecollegetextbookpdfs.com/# https://lightpdf.com/websites-download-pdf-books.html https://www.bookrix.com/books.html https://www.pdfdrive.com/ https://archive.org/search.php?query=books **https://www.openculture.com/free_textbooks** This is just a quick search...hope it helps