APA (7th ed.) Citation

(1991). Britannica book of the year 1991. Encyclopaedia Britannica.

Chicago Style (17th ed.) Citation

Britannica Book of the Year 1991. Chicago: Encyclopaedia Britannica, 1991.

MLA (9th ed.) Citation

Britannica Book of the Year 1991. Encyclopaedia Britannica, 1991.

Warning: These citations may not always be 100% accurate.