1. Accounting Department, School of Business, Nanjing University, Nanjing 210093, China
2. Department of Statistics, Yazd University, P.O. Box 89175-741,, Yazd, Iran
3. Department of Statistics, Faculty of Sciences, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
4. Department of Mathematics, Central Michigan University, Mt Pleasant 48859, MI, USA
5. Department of Mathematics, Faculty of Science, Helwan University, Cairo, Egypt
6. High Institute of Engineering and Technology, Ministry of Higher Education, El-Minia, Egypt