Variational inequalities for vector-valued functions. S. Hildebrandt; K.-O. Widman — 1979 Journal für die reine und angewandte Mathematik
Dirichlet's Boundary Value Problem for Harmonic Mappings of Riemannian Manifolds. S. Hildebrandt; H. Kaul; K.-O. Widman — 1976 Mathematische Zeitschrift
Harmonic Mappings and Minimal Submanifolds. J. Jost; S. Hildebrandt; K.-O. Widman Inventiones mathematicae
Littlewood-Paley a priori estimates for parabolic equations with sub-Dini continuous coefficients E. Fabes; S. Sroka; K.-O. Widman — 1979 Annali della Scuola Normale Superiore di Pisa - Classe di Scienze