%0 Journal Article %A Girg, Petr %T Existence of periodic solutions for a semilinear ordinary differential equation %J Electronic Journal of Differential Equations %D 1998 %V 1998 %I mathdoc %U http://geodesic.mathdoc.fr/item/EJDE_1998__1998__a28/ %G en %F EJDE_1998__1998__a28