Your Subject Specialist Librarian can help you locate Creative Commons and other openly licensed resources to use in your course as a textbook or supplemental learning materials, along with investigating library-licensed resources, which would be freely available to your students.
"Open" does not just mean it is available on the internet. Open Textbooks and Open Educational Resources (OER) must meet specific criteria to be considered "open".
First, they carry an open license. An open license is how the copyright holder (creator) of the Open Textbook or OER, grants the permissions of use. Creative Commons is the most common open license platform.
To truly be considered "open" a work or resource should be in the public domain or have a license that provides for the 5R's, which are:
Only the CC-BY Creative Commons license provides for use under the 5Rs. However, there are many Creative Commons licensed works that could be used that would still be no-cost to students, but may have restrictions on commercial use, remixing, or revising.
Many of the Open Licensed Open Textbooks and OER are created through institutional projects and authored by faculty in academic institutions, just like you. There are several Open Textbook and OER portals that have peer evaluation processes or peer reviews of resources. You can also consult with your Subject Specialist librarian, who can direct you to quality open materials.
Complete the MI ExplOER Certification modules to learn more about OER, copyright, open licensing, and how to adapt, adopt, or create your OER for your course.