Cita APA (7a ed.)

Darwin, C. R. (1971). The origin of species by means of natural selection ; The descent of man and selection in relation to sex. Encyclopaedia Britannica.

Cita Chicago Style (17a ed.)

Darwin, Charles Robert. The Origin of Species by Means of Natural Selection ; The Descent of Man and Selection in Relation to Sex. Chicago [etc.]: Encyclopaedia Britannica, 1971.

Cita MLA (9a ed.)

Darwin, Charles Robert. The Origin of Species by Means of Natural Selection ; The Descent of Man and Selection in Relation to Sex. Encyclopaedia Britannica, 1971.