Ridker, R. G. (1972). Population resources, and the environment. Government Printing Office.
Cita Chicago (17th ed.)Ridker, Ronald Gene. Population Resources, and the Environment. Washington, D.C: Government Printing Office, 1972.
Cita MLA (9th ed.)Ridker, Ronald Gene. Population Resources, and the Environment. Government Printing Office, 1972.
Atenció: Aquestes cites poden no estar 100% correctes.