E.I. Minakov1, A.S. Gublin2, E.Y. Shchetinin3, S.V. Prokopchina4

1,2 Tula State University (Tula, Russia)

3,4 Financial University under the Government of the Russian Federation (Moscow, Russia)

1 Eminakov@bk.ru, 2 GublinAS@yandex.ru, 3 eyshchetinin@fa.ru, 4 svprokopchina@fa.ru