George Mason University's OER Metafinder

Mason OER Metafinder searches 16 leading OER repositories with a single query. Users can perform broad queries across all sources or they can search for terms in full record, title, or author(s). They can also specify a date range and narrow their searches to a specific date range. 

1. American Memory (Library of Congress) 
2. AMSER - Applied Math and Science Education Repository 
3. BC Campus:Open Ed 
4. College Open Textbooks 
5. Digital Public Library of America 
6. Directory of Open Access Books (DOAB) 
7. HathiTrust - Full View 
8. Merlot.Org  
9. MIT OpenCourseware 
10. OAOpen.org 
11. OER Commons
12. OERs at Internet Archive
13. Open Textbook Library
14. OpenStax CNX
15. Project Gutenberg
16. World Digital Library

 

Source: Mason OER Metafinder