%0 Journal Article %A Timoumi, Mohsen %T Existence of periodic solutions for sub-linear first-order Hamiltonian systems %J Electronic Journal of Differential Equations %D 2015 %V 2015 %I mathdoc %U http://geodesic.mathdoc.fr/item/EJDE_2015__2015__a84/ %G en %F EJDE_2015__2015__a84