Gomez-Albarran, Mercedes, and Guillermo Jimenez-Diaz. “Recommendation and Students’ Authoring in Repositories of Learning Objects: A Case-Based Reasoning Approach”. International Journal of Emerging Technologies in Learning (iJET), vol. 4, Mar. 2009, pp. pp. 35-40, doi:10.3991/ijet.v4i0.797.