1. Laboratory of Topological Methods in Dynamics, National Research University Higher School of Economics, Nizhny Novgorod, 25/12 Bolshay Pecherskaya St., Nizhny Novgorod 603155, Russia
2. Institute of Electronic Engineering and Instrumentation, Yuri Gagarin State Technical University of Saratov, Politekhnicheskaya 77, Saratov 410054, Russia
3. Kotel’nikov’s Institute of Radio-Engineering and Electronics of RAS, Saratov Branch, Zelenaya 38, Saratov 410019, Russia