1. Department of Mathematics and Statistics, International Islamic University, Islamabad, Pakistan
2. Department of Mathematics, Taiz University, Taiz, Yemen
3. Department of Mathematics and Sciences, Prince Sultan University, Riyadh, Saudi Arabia
4. Institute of Mathematical Sciences, university of Malaya, Kuala Lumpur, Malaysia
5. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan