1. Department of Statistics, The University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
2. Department of Mathematics, Siirt University, Art and Science Faculty, 56100 Siirt, Turkey
3. Department of Mathematics, College of Science, Taif University, Taif 21944, Saudi Arabia
4. School of Mathematics and Statistics, Central South University, Changsha, 410083 Hunan, China