TY  - JOUR
AU  - Antonio Ambrosetti
AU  - V. Coti Zelati
TI  - Perturbation of Hamiltonian Systems with Keplerian Potentials.
JO  - Mathematische Zeitschrift
PY  - 1989
SP  - 227
EP  - 242
VL  - 201
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZ_1989__201_4_174049/
ID  - MZ_1989__201_4_174049
ER  -