@article{AIHPC_2006__23_4_439_0,
     author = {Berti, Massimiliano and Biasco, Luca},
     title = {Forced vibrations of wave equations with non-monotone nonlinearities},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {439--474},
     publisher = {Elsevier},
     volume = {23},
     number = {4},
     year = {2006},
     doi = {10.1016/j.anihpc.2005.05.004},
     mrnumber = {2245752},
     zbl = {1103.35076},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1016/j.anihpc.2005.05.004/}
}