1. School of Management and Economics, University of Electronic Science and Technology of China, Chengdu, P.R. China.
2. Center for West African Studies, University of Electronic Science and Technology of China, Chengdu, P.R. China.
3. College of Technology, University of Education, Winneba, Kumasi, Ghana.
4. School of Business, Sichuan Agricultural University, Yaan, P.R. China.