APA (7th ed.) Zitazioa
Harris, M., Mower, D., & Sikorzynska, A. Opportunities: Intermediate : Student's Book. Pearson.
Chicago Style (17th ed.) Zitazioa
Harris, Michael, David Mower, eta Anna Sikorzynska. Opportunities: Intermediate : Student's Book. Harlow, Inglaterra: Pearson.
MLA (9th ed.) Zitazioa
Harris, Michael, et al. Opportunities: Intermediate : Student's Book. Pearson.
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