1. Department of Mathematics, University of Management and Technology, Lahore 54770, Pakistan
2. Department of Mathematics and Statistics, The University of Lahore, Lahore 53700, Pakistan
3. School of Mathematics and Physics, China University of Geosciences, Wuhan 430074, China
4. Department of Mathematics, Faculty of Arts and Sciences, Cankaya University, 06530 Ankara, Turkey
5. Institute of Space Sciences, Magurele, P.O. Box MG-23, Ro 077125 Bucharest, Romania
6. Faculty of Engineering, University of Central Punjab, Lahore 54770, Pakistan