Duckworth, M. (2008). Countdown to first certificate: (Workbook CD). Oxford: Oxford University Press.
शिकागो स्टाइल उद्धरणDuckworth, Michael. Countdown to First Certificate: (Workbook CD). Oxford: Oxford University Press, 2008.
एमएलए उद्धरणDuckworth, Michael. Countdown to First Certificate: (Workbook CD). Oxford: Oxford University Press, 2008.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.