@article{EJDE_2005__2005__a15,
     author = {Bonanno, Gabriele and Livrea, Roberto},
     title = {Periodic solutions for a class of second-order {Hamiltonian} systems},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2005},
     year = {2005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2005__2005__a15/}
}