%0 Journal Article %A Massimiliano Pontecorvo %T Algebraic dimension of twistor spaces and scalar curvature of anti-self-dual metrics. %J Mathematische Annalen %D 1991 %P 113-122 %V 291 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/MAN_1991__291_1_164853/ %F MAN_1991__291_1_164853