%0 Journal Article
%A V. G. Durnev
%A O. V. Zetkina
%A A. I. Zetkina
%T On ``simple'' algorithmically undecidable fragments of elementary theory of an infinitely generated free semigroup
%J Čebyševskij sbornik
%D 2020
%P 56-71
%V 21
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CHEB_2020_21_4_a6/
%G ru
%F CHEB_2020_21_4_a6