%0 Journal Article
%A E. P. Bogomolova
%T Necessary conditions for the basis property in the direct sum of Sobolev spaces
%J Differencialʹnye uravneniâ
%D 1989
%P 722-723
%V 25
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1989_25_4_a19/
%G ru
%F DE_1989_25_4_a19