TY  - JOUR
AU  - M. V. Dolov
TI  - Differential equations $yy'=Q_4(x,y)$, having an ellipse as limit cycle
JO  - Differencialʹnye uravneniâ
PY  - 1967
SP  - 898
EP  - 904
VL  - 3
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1967_3_6_a2/
LA  - ru
ID  - DE_1967_3_6_a2
ER  -