%0 Journal Article
%A Antonio Ambrosetti
%A V. Coti Zelati
%T Perturbation of Hamiltonian Systems with Keplerian Potentials.
%J Mathematische Zeitschrift
%D 1989
%P 227-242
%V 201
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZ_1989__201_4_174049/
%F MZ_1989__201_4_174049