Clapham, W. B. (1981). Human ecosystems. Macmillan.
Lua i Stíl Chicago (17ú heag.)Clapham, Wentworth B. Human Ecosystems. New York: Macmillan, 1981.
Lua MLA (9ú heag.)Clapham, Wentworth B. Human Ecosystems. Macmillan, 1981.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.