Andrey Alexandrov, Chuvash State University, Cheboksary, Russia

Alexey Borisov, Udmurt State University, Izhevsk, Russia

Ivan Mamaev, Udmurt State University, Izhevsk, Russia

Alexander Ivanitsky, Chuvash State University, Cheboksary, Russia

Daria Troeshestova, Chuvash State University, Cheboksary, Russia