1. School of Mathematics and Statistics, Guizhou University of Finance and Economics, Guiyang 550025, China
2. School of Mathematics and Physics, University of South China, Hengyang 421001, China
3. School of Mathematics and Statistics, North China University of Water Resources and Electric Power, Zhengzhou 450046, China
4. Department of Mathematics and Statistics, The University of Lahore, Lahore, Pakistan
5. Department of Mathematics, School of Advanced Sciences, Kalasalingam Academy of Research and Education, Krishnankoil, India
6. Department of Applied Mathematics, University of Calcutta, Kolkata 700009, India