APA
Higgins J., . (1974). Indirect statements, part - 1: Unit 27. Longman Group Limited, London: .
Chicago
Higgins J.J, . 1974. Indirect statements, part - 1: Unit 27. Longman Group Limited, London: .
Harvard
Higgins J., . (1974). Indirect statements, part - 1: Unit 27. Longman Group Limited, London: .
MLA
Higgins J.J, . Indirect statements, part - 1: Unit 27. Longman Group Limited, London: . 1974.