APA

Ehrlich P. R., Ehrlich A. H. & Holdren J. P. (1973). Human ecology. San Francisco: W. H. Freeman.

Chicago

Ehrlich Paul R, Ehrlich Anne H and Holdren John P. 1973. Human ecology. San Francisco: W. H. Freeman.

Harvard

Ehrlich P. R., Ehrlich A. H. and Holdren J. P. (1973). Human ecology. San Francisco: W. H. Freeman.

MLA

Ehrlich Paul R, Ehrlich Anne H and Holdren John P. Human ecology. San Francisco: W. H. Freeman. 1973.