1. Faculty of Economics and Management, Hengyang Normal University, Hengyang 421002, China
2. School of Business, Hunan Normal University, Changsha 410081, China
3. Key Laboratory of Computing and Stochastic Mathematics (Ministry of Education), School of Mathematics and Statistics, Hunan Normal University, Changsha 410081, China
4. School of Finance, Henan University of Economics and Law, Zhengzhou 450016, China