APA (7th ed.) Citation

Darwin, C. (1929). The origin of species by means of natural selection (Last (6th) ed.). Watts & Co..

Chicago Style (17th ed.) Citation

Darwin, Charles. The Origin of Species by Means of Natural Selection. Last (6th) ed. London: Watts & Co., 1929.

MLA (9th ed.) Citation

Darwin, Charles. The Origin of Species by Means of Natural Selection. Last (6th) ed. Watts & Co., 1929.