I. A. Bilenko, G.S.Ivanov-Holodny, V.A. Kovalev
V. A. Kovalev - Ph.D. (Eng.), Senior Research, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) (Troitsk, Moscow). E-mail: viс.kov@yandex.ru
