1. Department of Basic Sciences, Deanship of Preparatory Year, King Faisal University Al Ahsa, Al Hofuf, Saudi Arabia
2. Department of Mathematical Sciences, United Arab Emirates University, P.O. Box 15551, Al Ain, UAE
3. Institute de Mathematiques de Jussieu-Paris Rive Gauche-Paris, France (Universite de Paris/Sorbonne Universite), Paris, France
4. CASPAM, Bahauddin Zakariya University, Multan 66000, Pakistan