Cita APA (7th ed.)
Ehrlich, P. R., Ehrlich, A. H., & Holdren, J. P. (1977). Ecoscience: Population, resources, environment. W. H. Freeman.
Cita Chicago (17th ed.)
Ehrlich, Paul R., Anne H. Ehrlich, i John P. Holdren. Ecoscience: Population, Resources, Environment. San Francisco: W. H. Freeman, 1977.
Cita MLA (9th ed.)
Ehrlich, Paul R., et al. Ecoscience: Population, Resources, Environment. W. H. Freeman, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.