1. Novosibirsk State Agrarian University, Novosibirsk, Russia
2. Regional Scientific and Educational Mathematical Center, Tomsk State University, Tomsk, Russia
3. Sobolev Institute of Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
4. Lomonosov Moscow State University, Moscow, Russia
5. Demidov Yaroslavl State University, Yaroslavl, Russia