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