TY  - JOUR
AU  - L. A. Cherkas
TI  - The number of limit cycles of a certain second order autonumous system
JO  - Differencialʹnye uravneniâ
PY  - 1976
SP  - 944
EP  - 946
VL  - 12
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1976_12_5_a21/
LA  - ru
ID  - DE_1976_12_5_a21
ER  -