TY  - JOUR
AU  - A. N. Vityuk
TI  - On the existence of an upper and a lower solution of a boundary value problem for a system of ordinary differential equations
JO  - Differencialʹnye uravneniâ
PY  - 1967
SP  - 1393
EP  - 1396
VL  - 3
IS  - 8
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1967_3_8_a18/
LA  - ru
ID  - DE_1967_3_8_a18
ER  -