Gaya APA

Ehrlich, P, R., Ehrlich, A, H. (1972). Population Resources Environment : Issues In Human Ecology (Edisi 2). San Fransisco: W.H. Freeman And Company.

Gaya MLA

Ehrlich, Paul, R.., Ehrlich, Anne, H.. "Population Resources Environment : Issues In Human Ecology". Edisi 2 San Fransisco: W.H. Freeman And Company, 1972. Teks.