Achasov, N. N.
Article History
Received: 20 December 2019
Revised: 16 January 2020
Accepted: 29 January 2020
First Online: 17 September 2020
ADDITIONAL INFORMATION
: Invited talk at the International Conference “Problems of Theoretical and Mathematical Physics” dedicated to the 110th anniversary of the birth of the outstanding Russian scientist—mathematician and physicist Nikolai Nikolaevich Bogolyubov, JINR, Dubna, September 11–13, 2019.