1. Department of Mathematical Sciences, College of Science, United Arab Emirates University, P. O. Box 15551, Al Ain, United Arab Emirates
2. College of Computer Science & Information Technology, Jazan University, Jazan, Saudi Arabia
3. Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan
4. Department of Mathematics, Government College University, Lahore 54000, Pakistan