Nordström, Gunnar (1881-1923)
- http://en.wikipedia.org/wiki/Gunnar_Nordstr%C3%B6m
- Wikipedia article about the Finnish physicist, who developed a relativistic theory of gravity that was an early competitor of general relativity, and who (together with Hans Reissner) found the solution to Einstein's field equations now known to describe a black hole with electric charge.
Penrose, Roger (1931-)
- http://www-history.mcs.st-andrews.ac.uk/Biographies/Penrose.html
- Biographical sketch of the British mathematician and physicist who developed the methods of global geometry, proved the first singularity theorem, invented a method for extracting energy from rotating black holes, and posited the cosmic censorship hypothesis; from the MacTutor History of Mathematics Archive (University of St. Andrews).
Shapiro, Irwin I.
- http://en.wikipedia.org/wiki/Irwin_Shapiro
- Wikipedia article about the American astrophysicist, one of the pioneers of solar-system tests of general relativity (Shapiro effect, deflection of light by gravity, perihelion precession of various planets).
Weyl, Hermann (1885-1955)
- http://www-history.mcs.st-andrews.ac.uk/~history/Biographies/Weyl.html
- Brief biography of the German mathematician who made pioneering contribution to group theory and the concept of symmetry, and was one of the first to formulate a unified theory of electromagnetism and general relativity; from the MacTutor History of Mathematics Archive (University of St. Andrews).