@article{GDZPPN002336499,
title = {Integrability of Hamiltonian systems and Birkhoff normal forms in the simple resonance case.},
journal = {Mathematische Annalen},
volume = {293},
year = {1992},
pages = {411-444},
zbl = {0735.58022},
url = {http://dml.mathdoc.fr/item/GDZPPN002336499}
}
Ito, Hidekazu. Integrability of Hamiltonian systems and Birkhoff normal forms in the simple resonance case.. Mathematische Annalen, Tome 293 (1992) pp. 411-444. http://gdmltest.u-ga.fr/item/GDZPPN002336499/