1. Department of Mathematics, Huzhou University, Huzhou, People's Republic of China
2. Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering, Changsha University of Science & Technology, Changsha, People's Republic of China
3. Department of Mathematics, School of Science, University of Management and Technology, Lahore, Pakistan
4. Department of Mathematics, COMSATS University Islamabad, Lahore, Pakistan