Open Textbook Store
- It calls itself a "Store," but they are not a publisher. Open TextBook Store provides freely and openly available math textbooks created by Washington CTC faculty.
- You can either download the whole book for free, or order a printed version which costs below 20 dollars.
- All textbooks on this site are licensed under CC BY 3.0.
- This license lets you distribute, remix, tweak, and build upon the original work, even commercially, as long as you credit the author for the original creation.
Source: "Open Textbook Store" by Open Washington: Open Educational Resources Network is licensed under CC BY 4.0