S.V. Ostakh1, М.Е. Bezrukov2, О.S. Ostakh1
1 Gubkin Russian State University of Oil and Gas (National Research University), 65 Leninsky Prospekt, Moscow, 119991, Russian Federation
E-mail: mironova_Ok@mail.ru
2 Lobachevsky State University of Nizhny Novgorod (UNN), 23 Prospekt Gagarina (Gagarin Avenue) BLDG 2, Nizhny Novgorod, 603950, Russian Federation
E–mail: mik38@yandex.ru
DOI: 10.33075/2220-5861-2018-2-38-43