1. Department of Mathematics and Statistics, Brock University, St. Catharines, ON L2S 3A1, Canada
2. Unit of Applied Statistics and Mathematics, Department of Energy and Technology, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden
3. Department of Mathematics and Statistics, University of Windsor, Windsor, ON N9B 3P4, Canada
4. Department of Statistics, Jahrom University, Jahrom 74137-66171, Iran