Features:

• Wikibooks may not look as fancy other open books providers but it is truly a community effort. Authors voluntarily start the book writing project, and readers can nominate them to be “featured books.”
• You can contribute to an existing Wikibook or start a new Wikibook. If you cannot find the openly available textbook in your discipline area, this is a nice place to begin the work.
• PDF versions are available for easy printing. To learn more about how to best utilize Wikibooks, please visit the Using Wikibooks page.

License Setting

• All Wikibooks are licensed under CC-BY-SA 3.0.
• This license lets you remix, tweak, and build upon the original work even for commercial purposes, as long as you credit the author and license your new creations under the identical terms.

Sample Attribution

Equation of waves (in the Fundamentals of Acoustics), from Acoustics by Jon (Jguk) is licensed under licensed under CC-BY-SA 3.0.