Do you know you could use the advanced search option in Google to look for OERs?
Simply scroll down to Usage Rights and select Free to use, share or modify, even commercially.
Mason OER Metafinder (MOM)About MOM:
The Mason OER Metafinder helps you find Open Educational Resources. Unlike other OER discovery sites (e.g, OER Commons, OASIS, MERLOT, OpenStax, etc.) with our Metafinder you aren’t searching a static database that we’ve built. Instead, the OER Metafinder launches a real-time, simultaneous search across 21 different sources of open educational materials as you hit the Search button.
Because it is a real-time, federated search, it can take a bit longer than searches of pre-indexed, curated content; however, as compensation the results returned are absolutely up-to-the-minute for each search target. Additional results will continue to trickle in as the search continues running and you begin examining your results.
A distinct feature of the Mason OER Metafinder is the scope of our discovery service. We’re searching well-known OER repositories like OpenStax, OER Commons, MERLOT but also sites like HathiTrust, DPLA, Internet Archive and NYPL Digital Collections where valuable but often overlooked yet often “open” educational materials may be found. Given the many “standards” of metadata in the OER universe, we can’t guarantee that every item retrieved is “Open” in the strictest interpretation of that term…so make it a practice to check the rights of any item you use.
About OASIS:
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 117 different sources and contains 388,707 records.
OASIS is being developed at SUNY Geneseo's Milne Library.