1. School of Economics, Qingdao University, Qingdao, China
2. School of Finance, Qilu University of Technology, Jinan, China
3. School of Business, Liaocheng University, Liaocheng, China
4. Qingdao Municipal Center for Disease Control & Preventation, Qingdao, China
5. Department of Economics and Public Policies, National University of Political Studies and Public Administration, Bucharest, Romania