APA

Soars J., Soars L., . (1987). Headway workbook upper-intermediate. Oxford: Oxford University Press.

Chicago

Soars John, Soars Liz, . 1987. Headway workbook upper-intermediate. Oxford: Oxford University Press.

Harvard

Soars J., Soars L., . (1987). Headway workbook upper-intermediate. Oxford: Oxford University Press.

MLA

Soars John, Soars Liz, . Headway workbook upper-intermediate. Oxford: Oxford University Press. 1987.