…………. (2011). Happy Earth.: Activity Book 1 (20.). OXFORD University Press.
Chicago Style (17th ed.) Citation…………. Happy Earth.: Activity Book 1. 20. New York: OXFORD University Press, 2011.
MLA (9th ed.) Citation…………. Happy Earth.: Activity Book 1. 20. OXFORD University Press, 2011.
Warning: These citations may not always be 100% accurate.