APA

Ehrlich P. R., Ehrlich A. H., . (1972). Population, resources, environment. San Francisco, California: W. H. Freeman and Company.

Chicago

Ehrlich Paul R, Ehrlich Anne H, . 1972. Population, resources, environment. San Francisco, California: W. H. Freeman and Company.

Harvard

Ehrlich P. R., Ehrlich A. H., . (1972). Population, resources, environment. San Francisco, California: W. H. Freeman and Company.

MLA

Ehrlich Paul R, Ehrlich Anne H, . Population, resources, environment. San Francisco, California: W. H. Freeman and Company. 1972.