The Scrum Guide
Ken Schwaber
Campbell's Physiology Notes for Nurses
John Lorimer Campbell
Hacking: The Art of Exploitation, 2nd Edition
Jon Erickson
The Real Projective Plane (includes Appendix for Mathematica®)
H. S. M. Coxeter & George Beck
The Great Depression: A History From Beginning to End
Hourly History
Beyond Good and Evil: Prelude to a Philosophy of the Future
Friedrich Wilhelm Nietzsche