Kupriyanov, Boris, Sergey Kosaretsky, Tatyana Mertsalova, and Tatiana Semenova. “Supplementary Education Institutions for Children (Data from Center for Statistics and Monitoring of Education)”. Voprosy obrazovaniya / Educational Studies Moscow, no. 2 (October 19, 2013): 209-231. Accessed May 6, 2024. https://vo.hse.ru/article/view/15456.