Citazione Stile APA (7a Edizione)

Harris, M., & Mower, D. S. (2000). Opportunities: Pre-intermediate : student's book.

Citazione stile Chigago Style (17a edizione)

Harris, Michael, e David Sikorzynska Mower. Opportunities: Pre-intermediate : Student's Book. Harlow, 2000.

Citatione MLA (9a ed.)

Harris, Michael, e David Sikorzynska Mower. Opportunities: Pre-intermediate : Student's Book. 2000.