APA (7th ed.) Zitazioa
Gum in the US. Euromonitor International Ltd.
Chicago Style (17th ed.) Zitazioa
Gum in the US. Euromonitor International Ltd.
MLA (9th ed.) Zitazioa
Gum in the US. Euromonitor International Ltd.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.