All these books are free to read: either they're distributed with a free license, or they're in the public domain.
These books are not included in Project Gutenberg.
keyword: Software – 70 free books.
These books are available in PDF format - good for desktops, printing.
David S. Evans et al.
Aseem Sharma et al.
$2 of thanks
from 2 ungluers
and 0 others
Sam Williams and Richard M. Stallman