Gaya APA

Ehrlich, P, R., Ehrlich, A, H. (1970). Population Resources Environment: Issues in Human Ecology . San Francisco: W. H. Freeman and Company.

Gaya MLA

Ehrlich, Paul, R.., Ehrlich, Anne, H.. "Population Resources Environment: Issues in Human Ecology". San Francisco: W. H. Freeman and Company, 1970. Art Original.