TY  - JOUR
AU  - A. P. Sadovskii
TI  - The conditions for the center of a certain system of differential equations
JO  - Differencialʹnye uravneniâ
PY  - 1971
SP  - 2285
EP  - 2286
VL  - 7
IS  - 12
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1971_7_12_a23/
LA  - ru
ID  - DE_1971_7_12_a23
ER  -