Convex Functions on Complete Noncompact Manifolds: Topological Structure. K. Shiohama; R.E. Greene — 1981 Inventiones mathematicae
A new version of differentiable sphere theorem. K. Shiohama; Y. Otsu; T. Yamaguchi — 1989 Inventiones mathematicae
Convex functions on complete noncompact manifolds : differentiable structure R. E. Greene; K. Shiohama — 1981 Annales scientifiques de l'École Normale Supérieure