Funding for this research was provided by:
The Tomsk State University Academic D.I. Mendeleev Fund Program (8.2.04.2018)
Text and Data Mining valid from 2020-02-14
Received: 4 December 2019
Accepted: 6 February 2020
First Online: 14 February 2020
Compliance with Ethical Standards
: The authors declare that they have no conflict of interest.