Ouadoud, M., M. Y. Chkouri, A. Nejjari, and K. E. El Kadiri. “Exploring a Recommendation System of Free E-Learning Platforms: Functional Architecture of the System”. International Journal of Emerging Technologies in Learning (iJET), vol. 12, no. 02, Feb. 2017, pp. pp. 219-226, doi:10.3991/ijet.v12i02.6381.