Gaya APA

Gude, K., Duckworth, M. (2008). Proficiency Masterclass Student's Book (Student edition (September 26, 2008). New York: Oxford University Press.

Gaya MLA

Gude, Kathy., Duckworth, Michael. "Proficiency Masterclass Student's Book". Student edition (September 26, 2008 New York: Oxford University Press, 2008. Text.