@article{RLIN_2005_9_16_2_a3,
     author = {Berti, Massimiliano and Biasco, Luca},
     title = {Periodic solutions of nonlinear wave equations with non-monotone forcing terms},
     journal = {Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Matematica e applicazioni},
     pages = {117--124},
     publisher = {mathdoc},
     volume = {Ser. 9, 16},
     number = {2},
     year = {2005},
     zbl = {1225.35147},
     mrnumber = {2186962},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RLIN_2005_9_16_2_a3/}
}