1. School of Economics, Qingdao University, Qingdao, China
2. School of Economics, Qingdao University, Qingdao, China; Faculty of Economics and Business Administration, West University of Timisoara, Timișoara, Romania
3. School of Economics, Qingdao University, Qingdao, China; Adnan Kassar School of Business, Lebanese American University, P.O. Box: 13-5063, Chouran, Beirut, Lebanon
4. Department of Finance, West University of Timisoara, Timisoara, Romania