Gude, K., & Duckworth, M. (1994). Proficiency masterclass: Student's book. Oxford: Oxford University Press.
Trích dẫn kiểu ChicagoGude, Kathy., và Michael Duckworth. Proficiency Masterclass: Student's Book. Oxford: Oxford University Press, 1994.
MLA引文Gude, Kathy., và Michael Duckworth. Proficiency Masterclass: Student's Book. Oxford: Oxford University Press, 1994.
警告：这些引文格式不一定是100％准确.