@article{AIHPC_1984__1_5_379_0,
     author = {Benci, V.},
     title = {Normal modes of a lagrangian system constrained in a potential well},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {379--400},
     publisher = {Gauthier-Villars},
     volume = {1},
     number = {5},
     year = {1984},
     mrnumber = {779875},
     zbl = {0561.58006},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPC_1984__1_5_379_0/}
}