H. Lazardholly et Wh. Meeks, A CLASSIFICATION OF GENUS ZERO MINIMAL-SU RFACES PROPERLY EMBEDDED INR-3 Z(2)/, Comptes rendus de l'Academie des sciences. Serie 1, Mathematique, 325(7), 1997, pp. 753-754
We prove that every genus zero minimal surface properly embedded in a
flat manifold R-3/Lambda, where Lambda is a lattice generated by two i
ndependent translations, must by a quotient of a doubly-periodic Scher
k surface.