Ehrlich, A. H., & Ehrlich, P. R. (1987). Earth. Thames Methuen.
Chicago Style aipamenaEhrlich, Anne H., and Paul R. Ehrlich. Earth. London: Thames Methuen, 1987.
MLA aipamenaEhrlich, Anne H., and Paul R. Ehrlich. Earth. Thames Methuen, 1987.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.