Duckworth, M. (2009). Countdown to first certificate. Oxford: Oxford University Press.
शिकागो स्टाइल उद्धरणDuckworth, Michael. Countdown to First Certificate. Oxford: Oxford University Press, 2009.
एमएलए उद्धरणDuckworth, Michael. Countdown to First Certificate. Oxford: Oxford University Press, 2009.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.