Машкова, Н. В., А. Ю. Байраншин, and Я. А. Матвеева. “Influence of Development of Competitiveness in Educational Service Market on Forming of Competitive Preferences of Supplementary Professional Education”. Modern Economics: Problems and Solutions, Vol. 11, May 2015, pp. 75-84, https://journals.vsu.ru/meps/article/view/4524.