Cita APA (7th ed.)

Soars, J., & Soars, L. (1987). Headway: Student's book. Upper-intemediate. Oxford University Press.

Cita Chicago (17th ed.)

Soars, John, i Liz Soars. Headway: Student's Book. Upper-intemediate. Oxford: Oxford University Press, 1987.

Cita MLA (9th ed.)

Soars, John, i Liz Soars. Headway: Student's Book. Upper-intemediate. Oxford University Press, 1987.