1. Department of Mathematics, Saint Xavier University, Chicago, IL 60655, USA
2. Department of Mathematics, Al-Zaytoonah University of Jordan, Amman 11733, Jordan
3. Biology Department, Faculty of Science and Arts, Al-Mikhwah, Al-Baha University, Al-Baha 1988, Saudi Arabia
4. Department of Mathematics, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
5. Department of Physics, Faculty of Science, Port Said University, Port Said 42521, Egypt