1. Department of Mathematics , School of Mathematics and Statistics, Guizhou University , Guiyang , Guizhou 550025 , P.R. China
2. Department of Mathematics , Xiangtan University , Xiangtan , Hunan 411105 , P.R. China ; Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science , King Abdulaziz University , Jeddah 21589 , Saudi Arabia
3. Department of Mathematical Analysis and Numerical Mathematics, Faculty of Mathematics, Physics and Informatics , Comenius University in Bratislava , Mlynská dolina, 842 48 Bratislava, Slovakia, and Mathematical Institute, Slovak Academy of Sciences, Štefánikova 49, 814 73 Bratislava , Slovakia