1. Kavun S, Mykhalchuk I, Kalashnykova N, Zyma A (2012) A method of internet-analysis by the tools of graph theory. In: Watada J, Phillips-Wren G, Jain LC, Howlett RJ (eds) Advances in intelligent decision technologies. Smart innovation, systems and technologies, vol 15, Part 1. Springer, Heidelber, Germany, pp 35–44. https://doi.org/10.1007/978-3-642-29977-3_4
2. Adkins SS (2016) The 2016–2021 worldwide self-paced eLearning market: the global eLearning market is in steep decline. http://www.ambientinsight.com . Last accessed 14 Apr 2019
3. E-Learning Market Trends & Forecast 2017–2021 Report (2016) A report by Docebo. Docebo S.p.A, London
4. Report and Forecast to 2017–2022 (2017) A report by Orbis Research. Dallas, Texas, June 15 2017. http://www.orbisresearch.com/contacts/request-sample/226355 . Last accessed 14 Apr 2019
5. Sucre F (2016) Role of E-learning in higher education in Latin America. Inter-American Dialogue, 12 Apr 2016. http://www.thedialogue.org/2016/04/role-of-e-learning-in-higher-education-in-latin-america . Accessed 14 Apr 2019 (2016)