Duckworth, M. (2009). Countdown to first certificate: (Student's book). Oxford: Oxford University Press.
Trích dẫn kiểu ChicagoDuckworth, Michael. Countdown to First Certificate: (Student's Book). Oxford: Oxford University Press, 2009.
Deismireacht MLADuckworth, Michael. Countdown to First Certificate: (Student's Book). Oxford: Oxford University Press, 2009.
Rabhadh: D'fhéadfadh nach mbeadh na deismireachtaí seo 100% cruinn i gcónaí.