APA (7th ed.) Zitazioa
Global Environmental Monitoring System. (1991). Urban air pollution. United nations environment health.
Chicago Style (17th ed.) Zitazioa
Global Environmental Monitoring System. Urban Air Pollution. Nairobi: United nations environment health, 1991.
MLA (9th ed.) Zitazioa
Global Environmental Monitoring System. Urban Air Pollution. United nations environment health, 1991.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.