%0 Journal Article %A Frans Oort %T Which Abelian Surfaces are Products of Elliptic Curves ? %J Mathematische Annalen %D 1975 %P 35-48 %V 214 %I mathdoc %U http://geodesic.mathdoc.fr/item/MAN_1975__214_162679/ %F MAN_1975__214_162679