Cita APA (7th ed.)

Swan, M. (1980). Practical english usage (1a. ed.). Oxford University Press.

Cita Chicago (17th ed.)

Swan, Michael. Practical English Usage. 1a. ed. Oxford: Oxford University Press, 1980.

Cita MLA (9th ed.)

Swan, Michael. Practical English Usage. 1a. ed. Oxford University Press, 1980.