1. School of Finance, Yunnan University of Finance and Economics, Kunming, China; Universidad Antonio de Nebrija, Madrid, Spain; School of Economics, Qingdao University, Qingdao, China
2. School of Economics, Qingdao University, Qingdao, China
3. Department of Finance, Faculty of Economics and Business Administration, West University of Timisoara, Timisoara, Romania
4. Department of Economics and Public Policies, National University of Political Studies and Public Administration, Bucharest, Romania