Walker, E., & Elsworth, S. (2000). Grammar practice for upper intermediate students. England: Longman.
Trích dẫn kiểu ChicagoWalker, Elaine., và Steve Elsworth. Grammar Practice for Upper Intermediate Students. England: Longman, 2000.
MLA CitationWalker, Elaine., và Steve Elsworth. Grammar Practice for Upper Intermediate Students. England: Longman, 2000.
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