———. 2005. Relativity: The Special and General Theory. Translated by R. W. Lawson, with introduction by R. Penrose, commentary by R. Geroch, historical essay by D. C. Cassidy (New York: Pi Press).

Einstein, A., and de Sitter, W. 1932. “On the Relation Between the Expansion and the Mean Density of the Universe.” Proceedings of the National Academy of Sciences, 18(3), 213.

Elgvin, T. D., Hermansen, J. S., Fijarczyk, A., Bonnet, T., Borge, T., Saether, S. A., Voje, K. L., and Saetre, G.-P. 2011. “Hybrid Speciation in Sparrows II: A Role for Sex Chromosomes?” Molecular Ecology, 20(18), 3823.

Elkin, L. O. 2003. “Rosalind Franklin and the Double Helix.” Physics Today, March, 42.

Else, L. 2011. “Nobel Psychologist Reveals the Error of Our Ways.” New Scientist (magazine issue 2839), online at: 222.newscientist.com/article/mg21228390.400-nobel-psychologist-reveals-the-err-of-our-ways.html.