TY  - JOUR
AU  - G. S. Rychkov
TI  - The absence in the equation $P_1(x,y)dx=(y-P_3(x))dy$ of limit cycles surrounding three singular points
JO  - Differencialʹnye uravneniâ
PY  - 1984
SP  - 1906
EP  - 1910
VL  - 20
IS  - 11
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1984_20_11_a7/
LA  - ru
ID  - DE_1984_20_11_a7
ER  -