APA (7th ed.) Citation

Richards, Hull, & Proctor. (1998). Changes: English for international communication 3 workbook. Cambridge University Press.

Chicago Style (17th ed.) Citation

Richards, Hull, and Proctor. Changes: English for International Communication 3 Workbook. UK: Cambridge University Press, 1998.

MLA (8th ed.) Citation

Richards, et al. Changes: English for International Communication 3 Workbook. Cambridge University Press, 1998.