I want to share the links to two great books about free software. You can download a free copy there or order a hardcopy.
Free as in freedom is a biography about Richard M. Stallman with revisions and comments by himself. I loved to read it because beside being a good biography of an important person in the free software movement it tells younger people like myself a lot about the history of Unix, GNU, GNU/Linux and the hacker movement.
Free software free society is a selection of great essays written by Richard M. Stallman