Poquet, O., V. Kovanović, P. de Vries, T. Hennis, S. Joksimović, D. Gašević, and S. Dawson. “Social Presence in Massive Open Online Courses”. The International Review of Research in Open and Distributed Learning, Vol. 19, no. 3, July 2018, doi:10.19173/irrodl.v19i3.3370.