Wei-qi, Liu
Jingxing, Zhang
Funding for this research was provided by:
National Social Science Fund Project (15BJY164)
the Ministry of Education Humanities and Social Sciences Fund Project (14YJA790034)
Article History
Received: 10 May 2017
Accepted: 28 December 2017
First Online: 24 January 2018
Competing interests
: The authors declare that we have no competing interests.