Blackall, Leigh, Paul Sharples, and Paul Sharples. “Saxef: A System for Automatic EXtraction of E-Learning Object Features”. Journal of e-Learning and Knowledge Society 3, no. 2 (November 16, 2009). Accessed September 22, 2020. https://www.je-lks.org/ojs/index.php/Je-LKS_EN/article/view/32.