Article History
Received: 21 March 2019
Accepted: 12 August 2019
First Online: 5 September 2019
Compliance with Ethical Standards
:
: Tatyana Ermolaeva declares that she has no conflict of interest. Olga Farafonova declares that she has no conflict of interest. Nadezhda Karaseva declares that she has no conflict of interest.The authors declare that they have no competing interests.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: Not applicable.