Collected Papers - Gesammelte Abhandlungen - Heinz Hopf - Google Books

http://books.google.de/books?id=DI4iWNdLDwAC&pg=PA121

From the preface: "Hopf algebras, Hopf fibration of spheres, Hopf-Rinow complete Riemannian manifolds, Hopf theorem on the ends of groups - can one imagine modern mathematics without all this? Many other concepts and methods, fundamental in various…