Richards, J. C., Hull, J., & Proctor, S. (1998). Changes: English for international communication : INTRO workbook. Cambridge: Cambridge University Press.
Παραπομπή Chicago StyleRichards, Jack C., Jonathan Hull, και Susan Proctor. Changes: English for International Communication : INTRO Workbook. Cambridge: Cambridge University Press, 1998.
Παραπομπή MLARichards, Jack C., Jonathan Hull, και Susan Proctor. Changes: English for International Communication : INTRO Workbook. Cambridge: Cambridge University Press, 1998.
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