APA (7th ed.) Citation

Duffy, C. B. a. M. (1992). Toefl. Heinemann.

Chicago Style (17th ed.) Citation

Duffy, Carolyn B and Mahnke. Toefl. Oxford: Heinemann, 1992.

MLA (9th ed.) Citation

Duffy, Carolyn B and Mahnke. Toefl. Heinemann, 1992.

Warning: These citations may not always be 100% accurate.