1. College of Humanities and Social Sciences, Nanjing University of Aeronautics and Astronautics, Jiangjun Road 29, Jiangning District, Nanjing 211106, China
2. Graduate School of Economics, Kyoto University, Yoshida-Honmachi, Sakyo-Ku, Kyoto 606-8501, Japan
3. College of Economics and Management, Nanjing University of Aeronautics and Astronautics, Jiangjun Road 29, Jiangning District, Nanjing 211106, China