1. Department of Applied Mathematics and Statistics, Institute of Space Technology, P. O. Box 2750, Islamabad 44000, Pakistan
2. Department of Mathematics, HITEC College, HIT Taxila Cantt, Pakistan
3. Institute of Mathematics, Khwaja Fareed University of Engineering & Information Technology, Rahim Yar Khan 64200, Pakistan
4. Department of Sciences and Humanities, National University of Computer and Emerging Sciences FAST Lahore, Pakistan