OpenStax

https://openstax.org/

"OpenStax is a nonprofit educational initiative based at Rice University, and it's our mission to give every student the tools they need to be successful in the classroom. Through our partnerships with philanthropic foundations and our alliance with other educational resource companies, we're breaking down the most common barriers to learning. Because we believe that a well-educated society profits us all.
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We publish high-quality, peer-reviewed, openly licensed college textbooks that are absolutely free online and low cost in print. Seriously. We've also developed a low-cost, research-based courseware that gives students the tools they need to complete their course the first time around. Check out our current library of textbooks and explore OpenStax Tutor Beta."

Schwerpunkte: Mathematik, Naturwissenschaften, Social Sciences, Humanities: bislang ein Titel -  "U.S. History is designed to meet the scope and sequence requirements of most introductory courses. The text provides a balanced approach to U.S. history, considering the people, events, and ideas that have shaped the United States from both the top down (politics, economics, diplomacy) and bottom up (eyewitness accounts, lived experience). U.S. History covers key forces that form the American experience, with particular attention to issues of race, class, and gender."