TY  - JOUR
AU  - G. S. Rychkov
TI  - A proof of the presence of an infinite number of limit cycles for the equation $\ddot y+\mu\ sin$ $(\dot y+\theta )+y=0$
JO  - Differencialʹnye uravneniâ
PY  - 1973
SP  - 1540
EP  - 1542
VL  - 9
IS  - 8
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1973_9_8_a22/
LA  - ru
ID  - DE_1973_9_8_a22
ER  -