1. School of Mathematics and Physical Sciences, Xuzhou Institute of Technology, Xuzhou 221008, Jiangsu, China
2. Department of Mathematics and Statistics, University of South Florida, Tampa, FL 33620, USA
3. Department of Mathematics, King Abdulaziz University, Jeddah, Saudi Arabia
4. Department of Mathematics, Zhejiang Normal University, Jinhua 321004, Zhejiang, China
5. College of Mathematics and Physics, Shanghai University of Electric Power, Shanghai 200090, China
6. College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao 266590, Shandong, China