%0 Journal Article
%A Z. I. Ismailov
%T Formally normal extensions of an operator
%J Differencialʹnye uravneniâ
%D 1992
%P 905-907
%V 28
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1992_28_5_a22/
%G ru
%F DE_1992_28_5_a22