APA (7th ed.) Citation

Soars, L., & Soars, L. (2010). American Headway 4: The world's most trusted English course (2a. ed.). Oxford University Press.

Chicago Style (17th ed.) Citation

Soars, Liz, and Liz Soars. American Headway 4: The World's Most Trusted English Course. 2a. ed. Nueva York: Oxford University Press, 2010.

MLA (9th ed.) Citation

Soars, Liz, and Liz Soars. American Headway 4: The World's Most Trusted English Course. 2a. ed. Oxford University Press, 2010.