OpenStax College provides your students with professional-quality textbooks that are free online and low-cost in print.

Our books are peer-reviewed and backed by top-of-the-line supporting materials. And while our books meet standard scope and sequence requirements, they are also customizable by you if your needs are different

Our initial search to find suitable existing open textbooks encompassed the following sites:

MERLOT
OER Commons
Connexions
Free Technology Academy
FLOSS Manuals
FlatWorldKnowledge
Free Book Centre
Global Text
The Saylor Foundation
Jorum’s collection of of open teaching materials “Open Educational Repository in Support of Computer Science”
BookBoon (quite a few potential texts at  but they are “free as in beer,” not open, and are advertising supported)