Whitney, N. (1994). Open doors (student's book 1): Có sách. Oxford: Oxford University Press.
शिकागो स्टाइल उद्धरणWhitney, Norman. Open Doors (student's Book 1): Có Sách. Oxford: Oxford University Press, 1994.
एमएलए उद्धरणWhitney, Norman. Open Doors (student's Book 1): Có Sách. Oxford: Oxford University Press, 1994.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.