Zawacki-Richter, Olaf, Eva Maria Baecker, and Sebastian Vogt. 2009. “Review of Distance Education Research (2000 to 2008): Analysis of Research Areas, Methods, and Authorship Patterns”. The International Review of Research in Open and Distributed Learning 10 (6), 21-50. https://doi.org/10.19173/irrodl.v10i6.741.