1. School of Mathematical Sciences, Nanjing Normal University, Nanjing, China
2. School of Mathematics and Statistics, Guizhou University, Guiyang, Guizhou, China
3. Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut, Egypt
4. Physics Department, Faculty of Science, University of Jeddah, Jeddah, Saudi Arabia
5. Department of Mathematics, Faculty of Science, Helwan University, Egypt