K. Yu. Ivanova
Chuvash State University named after I. N. Ulyanov, Cheboksary
Russian Federation

M. V. Kuzmin
Chuvash State University named after I. N. Ulyanov, Cheboksary
Russian Federation

L. G. Rogozhina
Chuvash State University named after I. N. Ulyanov, Cheboksary
Russian Federation

A. O. Patianova
Chuvash State University named after I. N. Ulyanov, Cheboksary
Russian Federation

V. L. Semenov
Chuvash State University named after I. N. Ulyanov, Cheboksary
Russian Federation

R. I. Alexandrov
Chuvash State University named after I. N. Ulyanov, Cheboksary
Russian Federation