%0 Journal Article
%A A. U. Muravitskii
%T Finite approximability of the~$I^\Delta$ calculus and the existence of an extension having no model
%J Matematičeskie zametki
%D 1981
%P 907-916
%V 29
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZM_1981_29_6_a11/
%G ru
%F MZM_1981_29_6_a11