Richards, J. C., Hull, J., & Proctor, S. (1990). Interchange: English for international communication. New York: Cambridge University Press.
Chicago Style aipamenaRichards, Jack C., Jonathan Hull, và Susan Proctor. Interchange: English for International Communication. New York: Cambridge University Press, 1990.
MLA aipamenaRichards, Jack C., Jonathan Hull, và Susan Proctor. Interchange: English for International Communication. New York: Cambridge University Press, 1990.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.