Murphy, R., & Smalzer, W. R. (2014). Grammar in use intermediate: Self-study reference and practice for students of North American English (Third edition, 15th printing.). Cambridge: Cambridge University Press.

Murphy, Raymond,, and William R. Smalzer. Grammar in Use Intermediate: Self-study Reference and Practice for Students of North American English. Third edition, 15th printing. Cambridge: Cambridge University Press, 2014.

Murphy, Raymond,, and William R. Smalzer. Grammar in Use Intermediate: Self-study Reference and Practice for Students of North American English. Third edition, 15th printing. Cambridge: Cambridge University Press, 2014.