Cita APA (7a ed.)

Seidl, J., & Swan, M. (1997). Basic English usage: Exercises with key (9th ed.). Oxford University Press.

Cita Chicago Style (17a ed.)

Seidl, Jennifer, y Michael Swan. Basic English Usage: Exercises with Key. 9th ed. Oxford: Oxford University Press, 1997.

Cita MLA (9a ed.)

Seidl, Jennifer, y Michael Swan. Basic English Usage: Exercises with Key. 9th ed. Oxford University Press, 1997.