If you need to cite your sources using a regular citation style, like APA or MLA, then you just simply add the CC or public domain license info at the end of your regular citation.
Claypool, R. (2012, October 5). Flamingo [Photograph]. Retrieved from https://flic.kr/p/dh7axD. CC BY license.
The OpenCourseWare (OCW) movement began in the United States with the Massachusetts Institute of Technology in 2002. This movement is university driven, and is focused on making the educational course materials that have been created by faculty available outside of the institution. The materials available vary by course, professor and even semester posed. Materials can include syllabi, written lectures, assignments, readings, videotaped lectures, and audio lectures.