1. Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, Dubna 141980, Russia
2. Department of Higher Mathematics, Dubna State University, Universitetskaya Str. 19, Dubna 141982, Russia
3. Institute of Mechanics and Energetics, Russian State Agrarian University — Moscow, Timiryazev Agricultural Academy, Moscow 127550, Russia