Cita APA (7a ed.)

Whitney, N. (1996). Open doors: Student's book. Oxford University Press.

Cita Chicago Style (17a ed.)

Whitney, Norman. Open Doors: Student's Book. New York, EUA: Oxford University Press, 1996.

Cita MLA (9a ed.)

Whitney, Norman. Open Doors: Student's Book. Oxford University Press, 1996.