%0 Journal Article
%A V. N. Gorbuzov
%A С. И. Kishkel
%T Apropos a theorem of Wittich
%J Differencialʹnye uravneniâ
%D 1987
%P 891-893
%V 23
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1987_23_5_a22/
%G ru
%F DE_1987_23_5_a22