Zawacki-Richter, O., Baecker, E. M., & Vogt, S. (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