1. Bernstein, Jeremy. 1996. A theory for everything. New York: Copernicus (Springer-Verlag).
2. Brush, Stephen. 2002. Cautious revolutionaries: Maxwell, Planck, Hubble. American Journal of Physics 70(2): 119–127 (February).
3. Einstein, Albert. 1960. Relativity: the special and the general theory. Fifteenth Edition. (trans: Robert W. Lawson in 1920.). London: Methuen & Co. This popular account was first published in German in 1917. This edition has five appendices, the last (1952) is titled “Relativity and the Problem of Space.”
4. Eisenstaedt, Jean. 2006. The curious history of relativity: how Einstein’s theory of gravity was lost and found again (trans: Arturo Sangalli.). Princeton/Oxford: Princeton University Press.
5. Farrell, John. 2005. The day without yesterday: lemaître, Einstein, and the birth of modern cosmology. New York: Thunder’s Mouth Press.