TY  - JOUR
AU  - V. V. Amel'kin
TI  - Existence of limit cycles of two-dimensional autonomous systems of differential equations
JO  - Differencialʹnye uravneniâ
PY  - 1988
SP  - 2027
EP  - 2032
VL  - 24
IS  - 12
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1988_24_12_a0/
LA  - ru
ID  - DE_1988_24_12_a0
ER  -