APA (7th ed.) Citation

Willems, M. (2005). Your pal Mo Willems presents Leonardo the terrible monster. Hyperion Books for Children.

Chicago Style (17th ed.) Citation

Willems, Mo. Your Pal Mo Willems Presents Leonardo the Terrible Monster. New York: Hyperion Books for Children, 2005.

MLA (8th ed.) Citation

Willems, Mo. Your Pal Mo Willems Presents Leonardo the Terrible Monster. Hyperion Books for Children, 2005.