Text and Data Mining valid from 2017-12-23
Received: 4 March 2016
Accepted: 29 November 2017
First Online: 23 December 2017
Compliance with ethical standards
: The author declares he has no conflict of interest.
: The datasets (1. code and programs, 2. data, and 3. readme files) used in this paper are available as electronic supplementary material of this article.