Affiliation: | 1.Kazan Federal University,Kazan,Russia;2.Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics,Eberhard Karls University,Tübingen,Germany;3.Special Astrophysical Observatory,Russian Academy of Sciences,Nizhnii Arkhyz,Karachai-Cherkessian Republic, Russia;4.Academy of Sciences of Tatarstan,Kazan,Russia |