Cita APA (7th ed.)

Ehrlich, P. R., & Ehrlich, A. H. (1972). Population, resources, environment: Issues in human ecology (2a. ed.). W. H. Freeman.

Cita Chicago (17th ed.)

Ehrlich, Paul R., i Anne H. Ehrlich. Population, Resources, Environment: Issues in Human Ecology. 2a. ed. San Francisco: W. H. Freeman, 1972.

Cita MLA (9th ed.)

Ehrlich, Paul R., i Anne H. Ehrlich. Population, Resources, Environment: Issues in Human Ecology. 2a. ed. W. H. Freeman, 1972.