Text and Data Mining valid from 2018-04-01
Received: 16 February 2018
Accepted: 8 March 2018
First Online: 23 April 2018
Compliance with ethical standards
: Shan Lu, Yong Cao, Sheng-Bo Fan, Zhen-Lin Chen, Run-Qian Fang, Si-Min He, and Meng-Qiu Dong declare that they have no conflict of interest.
: This article does not contain any studies with human or animal subjects performed by any of the authors.