1. School of Journalism and Communication, Xiamen University, Xiamen, Fujian Province, China
2. Department of Statistics, Yazd University, P.O. Box 89175-741, Yazd, Iran
3. Department of Mathematics, Al-Qunfudah University College, Umm Al-Qura University, Mecca, Saudi Arabia
4. Department of Mathematics, Faculty of Science, Helwan University, Helwan, Egypt
5. Department of Mathematical and Natural Sciences, Faculty of Engineering, Egyptian Russian University, Badr, Egypt