Nagel, S. S. (1974). Environmental politics. Praeger.
Lua i Stíl Chicago (17ú heag.)Nagel, Stuart S. Environmental Politics. New York: Praeger, 1974.
Lua MLA (9ú heag.)Nagel, Stuart S. Environmental Politics. Praeger, 1974.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.