@article{EJDE_2004__2004__a67,
     author = {Benevieri,  Pierluigi and Gavioli,  Andrea and Villarini,  Massimo},
     title = {Existence of periodic orbits for vector fields via {Fuller} index and the averaging method},
     journal = {Electronic journal of differential equations},
     year = {2004},
     volume = {2004},
     zbl = {1076.34044},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2004__2004__a67/}
}