Case, D., & Doug Case. (1990). English puzzles: 50 puzzles and games for practising your English. Oxford: Heinemann.
Chicago Style aipamenaCase, Doug, và Doug Case. English Puzzles: 50 Puzzles and Games for Practising Your English. Oxford: Heinemann, 1990.
MLA aipamenaCase, Doug, và Doug Case. English Puzzles: 50 Puzzles and Games for Practising Your English. Oxford: Heinemann, 1990.
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