1. Department of Mathematics, National College of Business Adminstration and Economics, Lahore, Pakistan
2. School of Mathematics, Minhaj University Lahore, Pakistan
3. Faculty of Science and Technology, University of the Faroe Islands, FO 100 Torshavn, Faroe Islands, Denmark
4. Department of Mathematics, College of Science, King Saud University, p.O. Box 2455, Riyadh 11451, Saudi Arabia
5. Department of Mathematics and Statistics, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia