APA (7th ed.) Citation

World Book, Inc. (2007). The Circulatory system. World Book.

Chicago Style (17th ed.) Citation

World Book, Inc. The Circulatory System. Chicago: World Book, 2007.

MLA (9th ed.) Citation

World Book, Inc. The Circulatory System. World Book, 2007.

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