%0 Journal Article
%A A. N. Vityuk
%T On the existence of an upper and a lower solution of a boundary value problem for a system of ordinary differential equations
%J Differencialʹnye uravneniâ
%D 1967
%P 1393-1396
%V 3
%N 8
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1967_3_8_a18/
%G ru
%F DE_1967_3_8_a18