Walker, E., Elsworth, S., & Nguyễn Văn Phước. (2001). Grammar practice for upper intermediate students (New ed.). Tp.HCM: Nxb Trẻ.
Παραπομπή Chicago StyleWalker, Elaine., Steve Elsworth, και Nguyễn Văn Phước. Grammar Practice for Upper Intermediate Students. New ed. Tp.HCM: Nxb Trẻ, 2001.
Παραπομπή MLAWalker, Elaine., Steve Elsworth, και Nguyễn Văn Phước. Grammar Practice for Upper Intermediate Students. New ed. Tp.HCM: Nxb Trẻ, 2001.
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