1. Faculty of Science for Girls, Department of Mathematics, King Abdulaziz University, Jeddah, Saudi Arabia
2. Faculty of Science, Department of Mathematics, King Abdulaziz University, Jeddah, Saudi Arabia
3. Faculty of Science, Department of Mathematics, Beni-Suef University, Beni-Suef, Egypt.
4. Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA