1. Department of Statistics, University of Sahiwal, Sahiwal, Punjab, Pakistan
2. Department of Mathematics, College of Science and Humanities in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
3. Department of Mathematics, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
4. Department of Biology, Yazd University, P.O. Box 89175-741, Yazd, Iran