Funding for this research was provided by:
Narodowe Centrum Nauki (DEC-2011/02/A/ST10/00284)
Text and Data Mining valid from 2018-08-28
Received: 17 November 2017
Accepted: 21 August 2018
First Online: 28 August 2018
Compliance with ethical standards
: On behalf of all authors, the corresponding author states that there is no conflict of interest.