1. College of Mathematics and Statistics, Shenzhen University, Shenzhen, People's Republic of China
2. Institute of Statistical Sciences, Shenzhen-Hong Kong Joint Research Center for Applied Statistical Sciences, Shenzhen University, Shenzhen, People's Republic of China
3. School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, People's Republic of China
4. Department of Mathematics and Statistics, University of Nevada, Reno, NV, USA