1. Department of Mathematics and Statistics, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
2. Tandy School of Computer Science, University of Tulsa, Tulsa, OK 74104, USA
3. Department of Mathematics, Government Associate College (W) Kamar Mashani, Mianwali 42400, Pakistan
4. Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan