1. Department of Mathematics, Faculty of Physical Sciences, University of Ilorin, P.M.B. 1515, Ilorin 240003, Nigeria
2. Department of Mathematics, Faculty of Science, The University of Jordon, Amman 11942, Jordan
3. Department of Physical Sciences, Landmark University, Omu-Aran 251103, Nigeria
4. Department of Mathematics, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia