School of Economics and Management, Neijiang Normal University,Neijiang, China. The Eeconomy Research Center of the West County, Neijiang,China.

Copyright © Yunqiang Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to Cite this Article

Download citation as EndNote