APA (7th ed.) Zitazioa
Summers, D. (1997). LONGMAN essential activator: Put your ideas into words. Longman.
Chicago Style (17th ed.) Zitazioa
Summers, Della. LONGMAN Essential Activator: Put Your Ideas into Words. England: Longman, 1997.
MLA (9th ed.) Zitazioa
Summers, Della. LONGMAN Essential Activator: Put Your Ideas into Words. Longman, 1997.
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