APA (7th ed.) Citation

Darwin, C. (1996). The origin of species by means of natural selection: The descent of man and selection in relation to sex (2nd ed., 6th pr.). Encyclopedia Britannica.

Chicago Style (17th ed.) Citation

Darwin, Charles. The Origin of Species by Means of Natural Selection: The Descent of Man and Selection in Relation to Sex. 2nd ed., 6th pr. Chicago [etc.]: Encyclopedia Britannica, 1996.

MLA (9th ed.) Citation

Darwin, Charles. The Origin of Species by Means of Natural Selection: The Descent of Man and Selection in Relation to Sex. 2nd ed., 6th pr. Encyclopedia Britannica, 1996.