%0 Journal Article
%A A. Katok
%A D. Bernstein
%T Birkhoff periodic orbits for small perturbations of completely integrable Hamiltonian Systems with convex Hamiltonians.
%J Inventiones mathematicae
%D 1987
%P 225-242
%V 88
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM_1987__88_143452/
%F IM_1987__88_143452