@article{EJDE_2008__2008__a6,
     author = {Chicone, Carmen and Felts, Kenny},
     title = {Non-monotone period functions for impact oscillators},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2008},
     year = {2008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2008__2008__a6/}
}