Open educational resources are "high-quality teaching, learning, and research materials that are free for people everywhere to use and repurpose" (Hewlett Foundation, 2018). Navigate through this guide to learn more about them.
Openly Available Sources Integrated Search (OASIS) is a search tool that aims to make the discovery of open content easier. OASIS currently searches open content from 72 different sources and contains 171,277 records.
Project Gutenberg offers over 57,000 free eBooks. Choose among free epub books, free kindle books, download them or read them online. You will find the world's great literature here, with focus on older works for which copyright has expired.