Ridker, R. G. (1972). Population resources, and the environment. Government Printing Office.
Lua i Stíl Chicago (17ú heag.)Ridker, Ronald Gene. Population Resources, and the Environment. Washington, D.C: Government Printing Office, 1972.
Lua MLA (9ú heag.)Ridker, Ronald Gene. Population Resources, and the Environment. Government Printing Office, 1972.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.