Cita APA (7th ed.)

Darwin, C., & Ridley, M. (1986). The essential Darwin. Unwin Hyman.

Cita Chicago (17th ed.)

Darwin, Charles, i Mark Ridley. The Essential Darwin. London: Unwin Hyman, 1986.

Cita MLA (9th ed.)

Darwin, Charles, i Mark Ridley. The Essential Darwin. Unwin Hyman, 1986.