TY  - JOUR
AU  - G. S. Rychkov
TI  - The maximal number of limit cycles of the system $\dot{y}=-x$, $\dot{x}=y-\sum_{i=0}^2a_i x^{2i+1}$ is equal to two
JO  - Differencialʹnye uravneniâ
PY  - 1975
SP  - 390
EP  - 391
VL  - 11
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1975_11_2_a23/
LA  - ru
ID  - DE_1975_11_2_a23
ER  -