@article{EJDE_1998__1998__a28,
     author = {Girg,  Petr},
     title = {Existence of periodic solutions for a semilinear ordinary differential equation},
     journal = {Electronic journal of differential equations},
     year = {1998},
     volume = {1998},
     zbl = {0917.34034},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_1998__1998__a28/}
}