APA (7th ed.) Zitazioa
Ash, R. (2007). Whitaker's world of facts. Penguin Books.
Chicago Style (17th ed.) Zitazioa
Ash, Russell. Whitaker's World of Facts. New Delhi: Penguin Books, 2007.
MLA (9th ed.) Zitazioa
Ash, Russell. Whitaker's World of Facts. Penguin Books, 2007.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.