Citazione Stile APA (7a Edizione)

Harris, M., & Mower, D. S. (2001). Opportunities: Elementary : student's book.

Citazione stile Chigago Style (17a edizione)

Harris, Michael, e David Sikorzynska Mower. Opportunities: Elementary : Student's Book. Harlow, 2001.

Citatione MLA (9a ed.)

Harris, Michael, e David Sikorzynska Mower. Opportunities: Elementary : Student's Book. 2001.