%0 Journal Article %A Nicklason, Gary R. %T Constant invariant solutions of the Poincaré center-focus problem %J Electronic Journal of Differential Equations %D 2010 %V 2010 %I mathdoc %U http://geodesic.mathdoc.fr/item/EJDE_2010__2010__a284/ %G en %F EJDE_2010__2010__a284