Khosravi, Hassan, Kirsty Kitto, and Joseph Jay Williams. “RiPPLE: A Crowdsourced Adaptive Platform for Recommendation of Learning Activities”. Journal of Learning Analytics 6, no. 3 (December 13, 2019): 91–105. Accessed February 20, 2020. https://epress.lib.uts.edu.au/journals/index.php/JLA/article/view/6373.