%0 Journal Article
%A L. Yu. Devyatkin
%T The set of closed classes $P_{k+1}$ that can be homomorphically mapped on $P_k$ has the cardinality of continuum
%J Vestnik Moskovskogo universiteta. Matematika, mehanika
%D 2020
%P 69-70
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/VMUMM_2020_1_a10/
%G ru
%F VMUMM_2020_1_a10