Ehrlich, P. R., & Ehrlich, A. H. Population, Resources, Environment: Issues In Human Ecology.
Cita Chicago (17th ed.)Ehrlich, Paul R., i Anne H. Ehrlich. Population, Resources, Environment: Issues In Human Ecology.
Cita MLA (9th ed.)Ehrlich, Paul R., i Anne H. Ehrlich. Population, Resources, Environment: Issues In Human Ecology.
Atenció: Aquestes cites poden no estar 100% correctes.