%0 Journal Article %A A. Ya. Khokhryakov %A B. M. Arkhipov %T A theorem on a differential inequality for a periodic boundary value problem for an ordinary differential equation of the second order %J Differencialʹnye uravneniâ %D 1965 %P 335-345 %V 1 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1965_1_3_a7/ %G ru %F DE_1965_1_3_a7