APA (7th ed.) Zitazioa
Worldwatch Institute. (2014). Vital signs. Island Press.
Chicago Style (17th ed.) Zitazioa
Worldwatch Institute. Vital Signs. Washington, District of Columbia: Island Press, 2014.
MLA (9th ed.) Zitazioa
Worldwatch Institute. Vital Signs. Island Press, 2014.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.