Funding for this research was provided by:
Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (PPZY2015A018)
Text and Data Mining valid from 2018-11-29
Received: 30 August 2018
Accepted: 15 November 2018
First Online: 29 November 2018
<!--Emphasis Type='Bold' removed-->Compliance with ethical standards
: The author declares that they have no conflict of interests.