singer, p. (1993). Practical Ethics (2nd.). cambridge University Press.
Lua i Stíl Chicago (17ú heag.)singer, peter. Practical Ethics. 2nd. Cambridge: cambridge University Press, 1993.
Lua MLA (9ú heag.)singer, peter. Practical Ethics. 2nd. cambridge University Press, 1993.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.