Darwin, C. R. 1., & Darwin, C. R. 1. (1950). The origin of species: By means of natural selection or the preservation of favored races in the struggle for life; and, The descent of men and selection in relation to sex. New York, New York: The Modern Library.

Darwin, Charles Robert 1809-1882, and Charles Robert 1809-1882 Darwin. The Origin of Species: By Means of Natural Selection or the Preservation of Favored Races in the Struggle for Life; And, The Descent of Men and Selection in Relation to Sex. New York, New York: The Modern Library, 1950.

Darwin, Charles Robert 1809-1882, and Charles Robert 1809-1882 Darwin. The Origin of Species: By Means of Natural Selection or the Preservation of Favored Races in the Struggle for Life; And, The Descent of Men and Selection in Relation to Sex. New York, New York: The Modern Library, 1950.