1. Department of Mathematics, COMSATS University, Islamabad, Pakistan
2. Division of Applied Mathematics, Thu Dau Mo University, Thu Dau Mot 75000, Vietnam
3. Ecole Normale Supéerieure de Meknés, Université Moulay Ismail, Meknes 50000, Morocco
4. Department of Medical Research, China Medical University Hospital, Taichung, Taiwan