1. School of Mathematics and Statistics, Xi’an Jiaotong University, Xi'an, China
2. Department of Mathematics, Women University of Azad Jammu and Kashmir, Bagh, AJK, Pakistan
3. Govt Akhtar Nawaz Khan (Shaheed) Degree College KTS, Haripur, Pakistan
4. Department of Statistics, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan