APA (7th ed.) Zitazioa
Soars, J., & Soars, L. American Headway: Student Book 4. Oxford University.
Chicago Style (17th ed.) Zitazioa
Soars, John, eta Liz Soars. American Headway: Student Book 4. Nueva York, EUA: Oxford University.
MLA (9th ed.) Zitazioa
Soars, John, eta Liz Soars. American Headway: Student Book 4. Oxford University.
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