Colvard, Nicholas B. ..., et al. "The Impact of Open Educational Resources on Various Student Success Metrics." International Journal of Teaching & Learning in Higher Education, vol. 30, no. 2, Apr. 2018, pp. 262-276.
Hilton, J. "Open Educational Resources and College Textbook Choices: A Review of Research on Efficacy and Perceptions." Educational Technology, Research and Development, 19 Feb. 2016, Accessed January 18, 2019.
American Council on Education, “Open Textbooks: The Current State of Play.” http://www.acenet.edu/news-room/Documents/Quick-Hits-Open-Textbooks.pdf April 2015. Accessed February 19, 2016.