APA (7e ed.) Bronvermelding

Singer, P. (2011). The expanding circle: Ethics, evolution, and moral progress. Princeton University Press.

Chicago (17e ed.) Bronvermelding

Singer, Peter. The Expanding Circle: Ethics, Evolution, and Moral Progress. Princeton: Princeton University Press, 2011.

MLA (8e ed.) Bronvermelding

Singer, Peter. The Expanding Circle: Ethics, Evolution, and Moral Progress. Princeton University Press, 2011.