Aleksandr Friedmann - A biography with reference to contemporaries, and a list of references.

Georg Riemann - Although he died before the development of general relativity, his work in non-Euclidean geometries is very important to studying a curved spacetime.

Georgio Ricci-Curbastro - The mathematician who developed much of tensor calculus before Einstein found a use for it.

Hermann Minkowski - A brief biography with quotations and a bibliography.

Hermann Weyl - One of the first people to combine general relativity with the laws of electromagnetism

Joao Magueijo - Theoretical physicist at Imperial College, who does not totally believe in Einstein's theories, especially the constant speed of light. Includes details about the author's views on the subject and courses being taught.

Karl Schwarzschild - A brief biography with reference to contemporary mathematicians and theories.

Karl Schwarzschild - The man who solved Einstein's equations and predicted the existence of black holes

Luigi Bianchi - A mathematician who developed many theorems regarding Riemannian geometry

Marcel Grossmann - 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.

Willem DeSitter - Mathematician who studied solution to general relativity and developed DeSitter space