1. School of Business, Sichuan Normal University, Chengdu 610101, China
2. Applied Mathematics Department, Koforidua Technical University, Koforidua P.O. Box KF 981, Ghana
3. College of Finance and Accounting, Lijiang Culture and Tourism College, Lijiang 674199, China
4. College of Movie and Media, Sichuan Normal University, Chengdu 610066, China