Wu, Kaijun
Wang, Tiejun
Wang, Chunli
Du, Tiaotiao
Lu, Huaiwei
Funding for this research was provided by:
the National Natural Science Foundation of China (11362008)
the National Social Science Foundation of China (15CGL001)
the Natural Science Fund Project of Gansu Province (148RJZA047)
the Basic Scientific Research Expenses of Finance Department of Gansu Province (214150)