Relativity and the Universe: A Popular Introduction Into Einstein's Theory of Space Time. E-book. Formato PDF Harry Schmidt   -  Forgotten Books, 2017  - 

I have to express my thanks to Dr. Karl Wichmann for kindly offering me an opportunity of inserting the corrections mentioned. It would cause me much pleasure if this English edition should contribute to the great object of spreading, as widely as possible, a knowledge of the fundamental ideas of Einstein's theory of relativity.