APA (7th ed.) Citation

Blough, G. O., & Campbell, M. H. (1955). When you go to the zoo. Whittlesey House.

Chicago Style (17th ed.) Citation

Blough, Glenn O., and Marjorie Haines Campbell. When You Go to the Zoo. New York: Whittlesey House, 1955.

MLA (9th ed.) Citation

Blough, Glenn O., and Marjorie Haines Campbell. When You Go to the Zoo. Whittlesey House, 1955.