@article{CMH_1989__64_1_140144,
     author = {Eduard Zehnder and Dietmar Salamon},
     title = {KAM theory in configuration space.},
     journal = {Commentarii mathematici Helvetici},
     pages = {84--132},
     year = {1989},
     volume = {64},
     number = {1},
     zbl = {0682.58014},
     url = {http://geodesic.mathdoc.fr/item/CMH_1989__64_1_140144/}
}