Duckworth, M. (1996). Open doors: Workbook 3. Oxford: Oxford University Press.
Dyfyniad Arddull ChicagoDuckworth, Michael. Open Doors: Workbook 3. Oxford: Oxford University Press, 1996.
Dyfyniad MLADuckworth, Michael. Open Doors: Workbook 3. Oxford: Oxford University Press, 1996.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.