@article{10_5427_jsing_2014_10l,
     author = {Jaume Llibre and Marco Antonio Teixeira},
     title = {Periodic solutions of discontinuous second order differential systems},
     journal = {Journal of Singularities},
     pages = {183--190},
     publisher = {mathdoc},
     volume = {10},
     year = {2014},
     doi = {10.5427/jsing.2014.10l},
     url = {http://geodesic.mathdoc.fr/articles/10.5427/jsing.2014.10l/}
}