N.V. Cherkesova1, G.A. Mustafaev2, A.G. Mustafaev3

1 Kabardino-Balkarian State University (Nalchik, Russia)
2 Dagestan State University of National Economy (Makhachkala, Russia)
1 natasha07_2002@mail.ru, 2 zoone@mail.ru, 3 arslan_mustafaev@mail.ru