Darwin Charles. (1952). The origin of species by means of natural selection. Enciclopaedia Britannica.
Citazione stile Chigago Style (17a edizione)Darwin Charles. The Origin of Species by Means of Natural Selection. Chicago: Enciclopaedia Britannica, 1952.
Citatione MLA (9a ed.)Darwin Charles. The Origin of Species by Means of Natural Selection. Enciclopaedia Britannica, 1952.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.