Rey Gómez, Rocío, Jorge Winston Barbosa Chacón, and Gilberto Gómez Mantilla. 2003. “EVALUATION OF SELF-LEARNING WRITTEN MATERIALS FOR DISTANCE EDUCATION”. RIED. Revista Iberoamericana de Educación a Distancia 6 (2):56-75. https://doi.org/10.5944/ried.6.2.1096.