Allen, M., Powell, D., & Dolby, D. (2007). IELTS graduation: Student's book. Macmillan.

Allen, Mark, Debra Powell, and Dickie Dolby. IELTS Graduation: Student's Book. Oxford: Macmillan, 2007.

Allen, Mark, et al. IELTS Graduation: Student's Book. Macmillan, 2007.