Karl Schwarzschild (Popularity: ): A brief biography with reference to contemporary mathematicians and theories. Hermann Minkowski (Popularity: ): A brief biography with quotations and a bibliography. Hendrik Lorentz (Popularity: ): Brief biography. Aleksandr Friedmann (Popularity: ): A biography with reference to contemporaries, and a list of references. Hermann Weyl (Popularity: ): One of the first people to combine general relativity with the laws of electromagnetism Marcel Grossmann (Popularity: ): A brief biography on Marcel Grossmann, a classmate of Einstein who was the first to find a connection between tensor calculus and the theory of relativity. Georg Riemann (Popularity: ): Although he died before the development of general relativity, his work in non-Euclidean geometries is very important to studying a curved spacetime. Willem DeSitter (Popularity: ): Mathematician who studied solution to general relativity and developed DeSitter space Georgio Ricci-Curbastro (Popularity: ): The mathematician who developed much of tensor calculus before Einstein found a use for it. Luigi Bianchi (Popularity: ): A mathematician who developed many theorems regarding Riemannian geometry Stephen Hawking: A Life in Science (Popularity: ): Complete text of the book by Michael White and John Gribbin, which tells the story of Hawking's life.