APA (7th ed.) Citation

(1990). Encyclopaedia Britannica (15th ed.). Encyclopaedia Britannica.

Chicago Style (17th ed.) Citation

Encyclopaedia Britannica. 15th ed. Chicago: Encyclopaedia Britannica, 1990.

MLA (9th ed.) Citation

Encyclopaedia Britannica. 15th ed. Encyclopaedia Britannica, 1990.

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