APA (7th ed.) Citation

Ehrlich, P. R., Ehrlich, A. H., & Holdren, J. P. (1973). Human ecology: Problems and solutions. Freeman.

Chicago Style (17th ed.) Citation

Ehrlich, Paul R., Anne H. Ehrlich, and John P. Holdren. Human Ecology: Problems and Solutions. San Francisco: Freeman, 1973.

MLA (9th ed.) Citation

Ehrlich, Paul R., et al. Human Ecology: Problems and Solutions. Freeman, 1973.