TY  - JOUR
AU  - N. A. Lukashevich
TI  - The isochronism of a center of certain systems of differential equations
JO  - Differencialʹnye uravneniâ
PY  - 1965
SP  - 295
EP  - 302
VL  - 1
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1965_1_3_a1/
LA  - ru
ID  - DE_1965_1_3_a1
ER  -