APA (7th ed.) Citation

Darwin, C. (1950). On the origin of the species by means of natural selection / by C. Darwin. Watts.

Chicago Style (17th ed.) Citation

Darwin, Charles. On the Origin of the Species by Means of Natural Selection / by C. Darwin. Watts, 1950.

MLA (9th ed.) Citation

Darwin, Charles. On the Origin of the Species by Means of Natural Selection / by C. Darwin. Watts, 1950.

Warning: These citations may not always be 100% accurate.