APA (7th ed.) Citation

(1984). The world book encylopedia W-X-Y-Z volume 21. World Books Inc.

Chicago Style (17th ed.) Citation

The World Book Encylopedia W-X-Y-Z Volume 21. Chicago: World Books Inc, 1984.

MLA (9th ed.) Citation

The World Book Encylopedia W-X-Y-Z Volume 21. World Books Inc, 1984.

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