Sage Books

"Sage Tutorial" by William Stein
Joyner - Differential Calculus with Sage — based on Granville's classic text book "Elements of the Differential and Integral Calculus"
Hoffmann, Stein, Joyner - Elements of Integral Calculus using Sage – PDF Book, preliminary version
Elementary Number Theory: Primes, Congruences, and Secrets by William Stein (preprint)
A First Course in Linear Algebra - The linear algebra textbook with freedom — HTML and PDF book by Robert Beezer
Sage for Newbies – by T. Kosan