Remarks on the Isoperimetric Inequality for Multiply-connected H-Surfaces. Helmut Kaul — 1972 Mathematische Zeitschrift
Ein Einschliessungssatz für H-Flächen in Riemannschen Mannigfaltigkeiten. Helmut Kaul — 1971 Manuscripta mathematica
Uniqueness of Harmonie Mappings and of Solutions of Elliptic Equations on Riemannnian Manifolds. Willi Jäger; Helmut Kaul — 1979 Mathematische Annalen
Rotationally symmetric harmonic maps from a ball into a sphere and the regularity problem for weak solutions of elliptic systems. Willi Jäger; Helmut Kaul — 1983 Journal für die reine und angewandte Mathematik
Uniqueness and Stability of Harmonic Maps and Their Jacobi Fields. Willi Jäger; Helmut Kaul — 1979 Manuscripta mathematica
Harmonic mappings into Riemannian manifolds with non-positive sectional curvature. Helmut Kaul; Stefan Hildebrandt; Kjell-Ove Widman — 1975 Mathematica Scandinavica