TY  - JOUR
AU  - L. M. Lerman
AU  - Ya. L. Umanskii
TI  - Isoenergetic classification of integrable Hamiltonian systems in a neighborhood of a simple elliptic point
JO  - Matematičeskie zametki
PY  - 1994
SP  - 88
EP  - 97
VL  - 55
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZM_1994_55_5_a8/
LA  - ru
ID  - MZM_1994_55_5_a8
ER  -