Funding for this research was provided by:
Polish Ministry of Science and Higher Education (DS 530-M045-D674-18, DS 530-8227-D494-18)
Text and Data Mining valid from 2019-10-22
Received: 8 May 2019
Accepted: 20 September 2019
First Online: 22 October 2019
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.