%0 Journal Article
%A G. S. Makanin
%T On the rank of coefficientless equations in four unknowns in a~free semigroup
%J Sbornik. Mathematics
%D 1976
%P 257-280
%V 29
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SM_1976_29_2_a9/
%G en
%F SM_1976_29_2_a9