@article{EJDE_2007__2007__a68,
     author = {Tomiczek,  Petr},
     title = {Remark on {Duffing} equation with {Dirichlet} boundary condition},
     journal = {Electronic journal of differential equations},
     year = {2007},
     volume = {2007},
     zbl = {1142.34314},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2007__2007__a68/}
}