TY  - JOUR
AU  - A. P. Sadovskii
TI  - Solution of the center and focus problem for a cubic system of nonlinear oscillations
JO  - Differencialʹnye uravneniâ
PY  - 1997
SP  - 236
EP  - 244
VL  - 33
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1997_33_2_a12/
LA  - ru
ID  - DE_1997_33_2_a12
ER  -