1. Department of Mathematics, College of Science, King Khalid University, 61413 Abha, Saudi Arabia
2. Polydisciplinary Faculty of Ouarzazate, P.O. Box: 638, Ouarzazate, Morocco
3. Department of Medical Research, China Medical University Hospital, China Medical University (Taiwan), Taichung, Taiwan
4. Department of Mathematics, Aligarh Muslim University, Aligarh 202 002, India