TY  - JOUR
AU  - I. Berstein
TI  - On the problem of periodical solutions of non-linear systems with a small parameter
JO  - Doklady Akademii Nauk
PY  - 1957
SP  - 9
EP  - 11
VL  - 113
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1957_113_1_a0/
LA  - ru
ID  - DAN_1957_113_1_a0
ER  -