@article{RLIN_1990_9_1_1_a5,
     author = {Omari, Pierpaolo and Villari, Gabriele},
     title = {Periodic solutions of the {Rayleigh} equation with damping of definite sign},
     journal = {Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Matematica e applicazioni},
     pages = {29--35},
     publisher = {mathdoc},
     volume = {Ser. 9, 1},
     number = {1},
     year = {1990},
     zbl = {0696.34030},
     mrnumber = {58045},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RLIN_1990_9_1_1_a5/}
}