rolston, H. Conserving natural value. columbia university press.
Lua i Stíl Chicago (17ú heag.)rolston, Holmes. Conserving Natural Value. New York: columbia university press.
Lua MLA (9ú heag.)rolston, Holmes. Conserving Natural Value. columbia university press.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.