Cita APA (7a ed.)

Gude, K., & Duckworth, M. (2002). Proficiency masterclass: Student's book. Oxford University Press.

Cita Chicago Style (17a ed.)

Gude, Kathy, y Michael Duckworth. Proficiency Masterclass: Student's Book. Oxford: Oxford University Press, 2002.

Cita MLA (9a ed.)

Gude, Kathy, y Michael Duckworth. Proficiency Masterclass: Student's Book. Oxford University Press, 2002.