Funding for this research was provided by:
Narodowe Centrum Nauki (2017/01/X/NZ9/00339)
Text and Data Mining valid from 2019-02-07
Received: 18 November 2018
Accepted: 19 January 2019
First Online: 7 February 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest regarding the publication of this article.