Duckworth, M., & Michael Duckworth; Kathy Gude. (1999). Countdown to First Certificate: Workbook with key and tapescripts. Oxford: Oxford University Press.
Παραπομπή Chicago StyleDuckworth, Michael, και Michael Duckworth; Kathy Gude. Countdown to First Certificate: Workbook With Key and Tapescripts. Oxford: Oxford University Press, 1999.
Παραπομπή MLADuckworth, Michael, και Michael Duckworth; Kathy Gude. Countdown to First Certificate: Workbook With Key and Tapescripts. Oxford: Oxford University Press, 1999.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.