%0 Journal Article
%A Hidekazu Ito
%T Convergence of Birkhoff normal forms for integrable systems.
%J Commentarii mathematici Helvetici
%D 1989
%P 412-461
%V 64
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMH_1989__64_1_140164/
%F CMH_1989__64_1_140164