APA (7th ed.) Citation

(1990). The 1990 World Book year book: The annual supplement to the World Book encyclopedia. World Book.

Chicago Style (17th ed.) Citation

The 1990 World Book Year Book: The Annual Supplement to the World Book Encyclopedia. Chicago: World Book, 1990.

MLA (8th ed.) Citation

The 1990 World Book Year Book: The Annual Supplement to the World Book Encyclopedia. World Book, 1990.

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