A.M. Lerer - D.Sc. (Phys.-Math.), Southern Federal University
E.V. Golovacheva - Ph.D. (Phys.-Math.), Southern Federal University
I.N. Ivanova - Post-graduent Student, Southern Federal University
I.A. Kazmin - Ph.D. (Phys.-Math.), Southern Federal University

A.M. Lerer, E.V. Golovacheva, I.N. Ivanova, I.A. Kazmin