%0 Journal Article
%A M. F. Raţă
%T Unsolvability of the problem of functional expressibility in the modal logic $\mathrm{S}4$
%J Doklady Akademii Nauk
%D 1983
%P 814-817
%V 268
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1983_268_4_a9/
%G ru
%F DAN_1983_268_4_a9