On the expansion of starshaped hypersurfaces by symmetric functions of their principal curvatures. John I.E. Urbas — 1990 Mathematische Zeitschrift
Global Hölder estimates for equations of Monge-Ampère type. John I.E. Urbas — 1988 Inventiones mathematicae
Regularity of Generalized Solutions of Monge-Ampère Equations. John I.E. Urbas — 1988 Mathematische Zeitschrift