1. School of Mathematics, Yunnan Normal University, Kunming, P.R. China
2. Department of Statistics, Tamkang University, Taipei, Taiwan, ROC
3. Department of Statistics, St. Anthony’s College, Shillong, India
4. Department of Mathematics, Indian Institute of Technology Patna, Patna, Bihar, India
5. School of Economics and Management, Shanxi University, Taiyuan, P.R. China