Richards, J. C., Hull, J., & Proctor, S. (1990). Interchange: English for international communication. New York: Cambridge University Press.
Παραπομπή Chicago StyleRichards, Jack C., Jonathan Hull, και Susan Proctor. Interchange: English for International Communication. New York: Cambridge University Press, 1990.
Παραπομπή MLARichards, Jack C., Jonathan Hull, και Susan Proctor. Interchange: English for International Communication. New York: Cambridge University Press, 1990.
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