Gaya APA

Ehrlich, H, A., Ehrlich, P, R. (1973). Human ecology : problems and solutions / Paul R. Ehrlich, Anne H. Erlich, John P. Holdren . : W.H. Freeman and Company.

Gaya MLA

Ehrlich, H., Anne., Ehrlich, Paul, R.. "Human ecology : problems and solutions / Paul R. Ehrlich, Anne H. Erlich, John P. Holdren". : W.H. Freeman and Company, 1973. Textbook.