1. Khan Academy coach demo. http://www.khanacademy.org/coach/demo. Khan Academy coach demo. http://www.khanacademy.org/coach/demo.
2. Semantic spiral timelines used as support for e-learning;Aguilar D. A. G.;J. UCS,2009
3. Studying learning in the worldwide classroom: Research into edX's first MOOC;Breslow L.;Research & Practice in Assessment,2013
4. Should your MOOC forum use a reputation system?