TY  - JOUR
AU  - Yu. A. Il'in
TI  - On the asymptotic perturbation of a nonlinear center
JO  - Differencialʹnye uravneniâ
PY  - 1997
SP  - 632
EP  - 637
VL  - 33
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1997_33_5_a9/
LA  - ru
ID  - DE_1997_33_5_a9
ER  -