TY  - JOUR
AU  - V. V. Amel'kin
TI  - Isochrony in cases of a center and a structurally unstable focus
JO  - Differencialʹnye uravneniâ
PY  - 1982
SP  - 1073
EP  - 1075
VL  - 18
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1982_18_6_a18/
LA  - ru
ID  - DE_1982_18_6_a18
ER  -