Cita APA (7a ed.)

Darwin, C., Barrett, P. H., & Freeman, R. B. (1988). Variation of animals and plants under domestication, 2. Pickering.

Cita Chicago Style (17a ed.)

Darwin, Charles, Paul H. Barrett, y R. B. Freeman. Variation of Animals and Plants Under Domestication, 2. London: Pickering, 1988.

Cita MLA (8a ed.)

Darwin, Charles, et al. Variation of Animals and Plants Under Domestication, 2. Pickering, 1988.