APA (7th ed.) Citation

BOIS, W. P. D. The Twenty-One Balloons. The Viking Press.

Chicago Style (17th ed.) Citation

BOIS, William Pene Du. The Twenty-One Balloons. The Viking Press.

MLA (8th ed.) Citation

BOIS, William Pene Du. The Twenty-One Balloons. The Viking Press.

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