APA (7th ed.) Citation

Irons, W. (1991). How did morality evolve? Zygon, 26(1), 49.

Chicago Style (17th ed.) Citation

Irons, William. "How Did Morality Evolve?" Zygon 26, no. 1 (1991): 49.

MLA (8th ed.) Citation

Irons, William. "How Did Morality Evolve?" Zygon, vol. 26, no. 1, 1991, p. 49.