1. College of Mathematics and Computer Science, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
2. Department of Mathematics, King Abdulaziz University, Jeddah 21589, Saudi Arabia
3. Department of Mathematics and Statistics, University of South Florida, Tampa, FL 33620-5700, USA
4. School of Mathematical and Statistical Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa
5. Department of Mathematics, University of Management and Technology, Lahore 54770, Pakistan
6. Department of Mathematics, Cankaya University, Etimesgut, Ankara 06790, Turkey
7. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 404332, Taiwan
8. Department of Geography, Government College University Lahore 54000, Pakistan