Ludwig Hopf

Ludwig Hopf (23 October 1884 in Nürnberg, Germany – 23 December 1939 in Dublin) was a German-Jewish theoretical physicist who made contributions to mathematics, special relativity, hydrodynamics, and aerodynamics. Early in his career he was the assistant to and a collaborator and co-author with Albert Einstein. Provided by Wikipedia

1
by Hopf, Ludwig
Published 1931
Springer Berlin Heidelberg

2
by Hopf, Ludwig
Published 1936
Springer Berlin Heidelberg