1. Department of Mathematics, College of Science and Technology, Covenant University, Canaanland, KM 10, Idiroko Road, Ota, Ogun State, Nigeria
2. Department of Mathematics, School of Physical Sciences, Federal University of Technology Owerri, P.M.B. 1526 Owerri, Imo State, Nigeria
3. Department of Mathematics, University of Uyo, Uyo, Nigeria
4. Department of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban, South Africa
5. Department of Mathematics and Sciences, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia
6. Department of Medical Research, China Medical University, Taichung 40402, Taiwan
7. Department of Mathematical Sciences, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia