Saylor Academy's Open Licenses Tutorial
Read this information on open content licenses, openly licensed educational resources (OER), and why Saylor Academy has decided to use this kind of material. At the bottom of the page, there are a few suggestions for where to find OERs: Creative Commons Search, Google Advanced Search, and Wikimedia Commons.
Click https://www.saylor.org/how-do-i-figure-out-whether-something-is-openly-licensed/ link to open resource.