Biber, D. (1999). Longman grammar of spoken and written English. New York: Longman.
Citación estilo ChicagoBiber, Douglas. Longman Grammar of Spoken and Written English. New York: Longman, 1999.
Cita MLABiber, Douglas. Longman Grammar of Spoken and Written English. New York: Longman, 1999.
Precaución: Estas citas no son 100% exactas.