Gude, K., & Duckworth, M. (1998). Proficiency masterclass: Workbook with answers. Oxford: Oxford University Press.
Trích dẫn kiểu ChicagoGude, Kathy., và Michael Duckworth. Proficiency Masterclass: Workbook With Answers. Oxford: Oxford University Press, 1998.
MLA引文Gude, Kathy., và Michael Duckworth. Proficiency Masterclass: Workbook With Answers. Oxford: Oxford University Press, 1998.
警告：這些引文格式不一定是100％准確.