Hans Schwerdtfeger

Hans Wilhelm Eduard Schwerdtfeger (9 December 1902 – 26 June 1990) was a German-Canadian-Australian mathematician who worked in Galois theory, matrix theory, theory of groups and their geometries, and complex analysis.

"In 1962 he published ''Geometry of Complex Numbers: Circle Geometry, Möbius Transformations, Non-Euclidean Geometry'' which: ... should be in every library, and every expert in classical function theory should be familiar with this material. The author has performed a distinct service by making this material so conveniently accessible in a single book. " - Provided by Wikipedia