Παραπομπή APA

Keller, D. R. (2010). Environmental ethics: The big questions. Wiley-Blackwell.

Παραπομπή Chicago Style

Keller, David R. Environmental Ethics: The Big Questions. U.S.A.: Wiley-Blackwell, 2010.

Παραπομπή MLA

Keller, David R. Environmental Ethics: The Big Questions. Wiley-Blackwell, 2010.