%0 Journal Article %A Fernando Torres %T Weierstrass points and double converings of curves. With application: Symmetric numerical semigroup which cannot be realized as Weierstrass semigroups. %J Manuscripta mathematica %D 1994 %P 39-58 %V 83 %N 3-4 %I mathdoc %U http://geodesic.mathdoc.fr/item/MM2_1994__83_3-4_155946/ %F MM2_1994__83_3-4_155946