Cita APA (7a ed.)

Swan, M., & Smith, B. (1991). Learner english: A teacher's guide to interference and other problems (5th print.). Cambridge University Press.

Cita Chicago Style (17a ed.)

Swan, Michael, y Bernard Smith. Learner English: A Teacher's Guide to Interference and Other Problems. 5th print. Cambridge: Cambridge University Press, 1991.

Cita MLA (9a ed.)

Swan, Michael, y Bernard Smith. Learner English: A Teacher's Guide to Interference and Other Problems. 5th print. Cambridge University Press, 1991.