T.G. Artyushina - Ph. D. (Eng.), Associate Professor, Department «Higher Mathematics», Plekhanov Russian University of Economics (Moscow)
E-mail: t.g.art@yandex.ru
G.I. Bobrik - Ph. D. (Phys.-Math.), Associate Professor, Department «Higher Mathematics», Plekhanov Russian University of Economics (Moscow)
E-mail: bobrikgi@mail.ru