%0 Journal Article %A Aberra, Dawit %T On a generalized reflection law for functions satisfying the Helmholtz equation %J Electronic Journal of Differential Equations %D 1999 %V 1999 %I mathdoc %U http://geodesic.mathdoc.fr/item/EJDE_1999__1999__a123/ %G en %F EJDE_1999__1999__a123