1. CASPAM, Bahauddin Zakariya University, Multan, Pakistan
2. Department of Mathematics, Islamia College Peshawar, Khyber Pakhtunkhwa, Pakistan
3. Department of Mathematics, Forman Christian College (A Chartered University), Lahore, Pakistan
4. Institute de Mathematiques de Jussieu-Paris Rive Gauche-Paris, Paris, France