1. Department of Statistics, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Iran
2. Department of Statistics, Mathematics & Insurance, Benha University, Benha, Egypt
3. Faculty of Mathematics, University of Sistan and Baluchestan, Zahedan, Iran
4. Department of Statistics, College of Sciences, Shiraz University, Shiraz, Iran
5. Department of Mathematics, Statistics & Computer Science, Marquette University, WI 53233, U.S.A.