APA (7th ed.) Zitazioa
(1981). Science year :1981: The World book science annual. Field Enterprises Educational Corporation.
Chicago Style (17th ed.) Zitazioa
Science Year :1981: The World Book Science Annual. Chicago: Field Enterprises Educational Corporation, 1981.
MLA (9th ed.) Zitazioa
Science Year :1981: The World Book Science Annual. Field Enterprises Educational Corporation, 1981.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.