Green, D., & Diana Green; Sandra Allen; Nguyễn Quốc Hùng. (1999). English in focus level C: Workbook. Tp. Hồ Chí Minh: Nxb. Tp. Hồ Chí Minh.
शिकागो स्टाइल उद्धरणGreen, Diana, और Diana Green; Sandra Allen; Nguyễn Quốc Hùng. English in Focus Level C: Workbook. Tp. Hồ Chí Minh: Nxb. Tp. Hồ Chí Minh, 1999.
एमएलए उद्धरणGreen, Diana, और Diana Green; Sandra Allen; Nguyễn Quốc Hùng. English in Focus Level C: Workbook. Tp. Hồ Chí Minh: Nxb. Tp. Hồ Chí Minh, 1999.
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