Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

Ehrlich, Paul R., y A. H. Ehrlich. Population Resources Environment: Issues in Human Ecology. 2nd ed. San Francisco: Freeman, 1972.

Cita MLA (9a ed.)

Ehrlich, Paul R., y A. H. Ehrlich. Population Resources Environment: Issues in Human Ecology. 2nd ed. Freeman, 1972.