एपीए उद्धरण

Duckworth, M., & Michael Duckworth; Kathy Gude. (1999). Countdown to First Certificate: Workbook with key and tapescripts. Oxford: Oxford University Press.

शिकागो स्टाइल उद्धरण

Duckworth, Michael, और Michael Duckworth; Kathy Gude. Countdown to First Certificate: Workbook With Key and Tapescripts. Oxford: Oxford University Press, 1999.

एमएलए उद्धरण

Duckworth, Michael, और Michael Duckworth; Kathy Gude. Countdown to First Certificate: Workbook With Key and Tapescripts. Oxford: Oxford University Press, 1999.