1. Department of Mathematics, Kinnaird College for Women, Lahore, Pakistan
2. Department of Mathematics, University of the Punjab, Lahore, Pakistan
3. Basic Sciences Department, Preparatory Year Deanship, King Faisal University, Al-Ahsa 31982, Saudi Arabia
4. Department of Mathematics, Faculty of Basic andApplied Sciences, Air University, PAF Complex E-9, Islamabad, Pakistan