OpenStax
openstax.org
Free, peer-reviewed college textbooks covering math, science, business, and humanities — funded by Rice University and philanthropic grants.
Why it is useful
OpenStax textbooks are written and peer-reviewed by the same caliber of academics as commercial textbooks, but are free to read online, download as PDF, or buy in low-cost print — a direct answer to $200+ textbook prices. Many US colleges have officially adopted OpenStax texts for intro-level courses.
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