1. School of Management, University of Science & Technology of China, Hefei, Anhui 230026, P. R. China
2. School of Management, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
3. Robert B. Willumstad School of Business, Adelphi University, Garden City, NY 11530-0701, US
4. School of Management and Economics, Beijing Institute of Technology, Beijing 100081, P. R. China