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Here is a link to almost any textbook's free PDF version. : r/unt
Open Textbook Library - Open Textbook Library - Center for Open …
8 Websites to Download PDF Textbooks for Free (Updated 2020)
OpenStax | Free Textbooks Online with No Catch
ZLibrary – Download Free eBooks, PDFs & Textbooks Online
Z-Library – the world’s largest e-book library. Your gateway to ...
10 Free Textbook PDF Websites for Easy Learning - Dollarsanity
Guide to Open, Free, & Affordable Course Materials: eTextbooks
200 Free Textbooks: A Meta Collection - Open Culture
Innovative OER Platform - LibreTexts