Isoparametric Hypersurfaces with Four or Six Distinct Principal Curvatures. Necessary Conditions on the Multiplicities. U. Abresch — 1983 Mathematische Annalen
Constant mean curvature tori in terms of elliptic functions. U. Abresch — 1987 Journal für die reine und angewandte Mathematik
Lower curvature bounds, Toponogov's theorem, and bounded topology. II U. Abresch — 1987 Annales scientifiques de l'École Normale Supérieure