APA (7th ed.) Citation

Henkes, K., & Lobel, A. (2005). So happy! Greenwillow Books.

Chicago Style (17th ed.) Citation

Henkes, Kevin, and Anita Lobel. So Happy! [New York]: Greenwillow Books, 2005.

MLA (8th ed.) Citation

Henkes, Kevin, and Anita Lobel. So Happy! Greenwillow Books, 2005.