Morzhin, O. V.
Pechen, A. N.
Article History
Received: 8 May 2021
Revised: 20 May 2021
Accepted: 25 May 2021
First Online: 19 October 2021
ADDITIONAL INFORMATION
: O. V. Morzhin http://www.mathnet.ru/eng/person30382; A. N. Pechen is a corresponding author, http://www.mathnet.ru/eng/person17991.