| Affiliation: | 1. Department of Mathematics, Anhui Normal University, Wuhu 241000, Anhui, PR China;2. Rolf Nevanlinna Institute, Department of Mathematics and Statistics, University of Helsinki, P.O. Box 68, Fin-00014, Finland;1. Municipal budget educational establishment of higher education «Samara Academy of State and Municipal Management», 96 Stara Zagora Street, Samara 443084, Russia;2. Samara State Aerospace University (SSAU), 34, Moskovskoe shosse, Samara, 443086, Russia;1. Department of Mathematics, Sun Yat-sen University, Guangzhou, 510275, China;2. Faculty of Information Technology, Macau University of Science and Technology, Macau, China |
