Try using MERLOT's ISBN search tool to search for materials related to a certain textbook.
In addition to using the search engines and repositories linked on this guide, you can also use advanced search features when searching Google, YouTube or Flickr, to find and locate OER. You will still need to confirm the individual license of the object you select to assure it meets the appropriate CC license.
Google Advanced Search - Under Usage Rights select to limit your results to resources which are free to use, modify or share. More from Google on Usage Rights.
YouTube - After searching by keyword in YouTube, use the Filters feature to filter your results to videos with a Creative Commons License.
Flickr - After searching by keyword in Flickr, use the Any License filter feature to filter your results to the appropriate usage license which best suits your usage of the work.
Creative Commons - Creative Commons' search engine searches various websites for open-licensed and public domain works.
Need help finding OER that works for your needs? Ask a librarian for help! Snowden's librarians are experts at finding and evaluating sources, including OER.