Vaganova, O. I., Sirotyk, S. D., Popkova, A. A., Smirnova, Z. V., & Bulaeva, M. N. (2019). Additional education in higher professional educational institution. Amazonia Investiga, 8(22), 305–310. Retrieved from https://amazoniainvestiga.info/index.php/amazonia/article/view/448