1. Department of Mathematical Sciences, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
2. Department of Mathematics, Guangdong University of Petrochemical Technology, Maoming, China
3. Department of Statistics, The Islamia University of Bahawalpur (IUB), Bahawalpur, Pakistan
4. School of Mathematics and Statistics, Central South University, Hunan, China