Quasi-umbilical hypersurfaces of a Sasakian manifold
The author states two characterizations of totally umbilical and totally geodesic hypersurfaces among the class of quasi-umbilical hypersurfaces of a Sasakian manifold. He also states a sufficient condition for a totally umbilicial hypersurface in a Sasakian manifold to be isometric to an ordinary sphere. No proofs are given.
scientific article; zbMATH DE number 940619