Funding for this research was provided by:
National Natural Science Foundation of China (71501052)
Natural Science Foundation of Guangdong Province (2015A030310506)
Philosophy and Social Science Planning Program of Guangdong Province (GD16XGL38)
Philosophy and Social Science Planning Program of Guangzhou (2016GZQN32)
Article History
Received: 19 January 2018
Revised: 9 February 2018
Accepted: 12 February 2018
First Online: 3 March 2018