1. Department of General and Theoretical Physics, Bashkir State Pedagogical University, Okt. Revolutsii Street 3A, Ufa 450000, Russia
2. Department of Physics, Ufa State Petroleum Technological University, Kosmonavtov Street 1, Ufa 450062, Russia
3. Academy of Sciences of Bashkortostan, Kirova Street 15, Ufa 450008, Russia