%0 Journal Article
%A V. G. Durnev
%T Positive theory of a free semigroup
%J Doklady Akademii Nauk
%D 1973
%P 772-774
%V 211
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1973_211_4_a3/
%G ru
%F DAN_1973_211_4_a3