OER Textbooks
OASIS (Openly Available Sources Integrated Search) - Produced by librarians at SUNY Geneseo, this database contains more than 155,000 records from 52 different sources. Lots of search options, such as limiting by license, type, or source.
Mason OERMetafinder - Technically, a discovery service that simultaneously searches 17 sources of open educational materials. Goes beyond traditional OER sources to includes resources such as HathiTrust, Project Gutenberg, and the American Memory Project.
A-Z Affordable Learning Database (OhioLINK) - This is a searchable list of more than 1,000 materials that are Open Access, Open Educational, or OhioLINK licensed resources that are no cost to Ohio higher education students.