Cita APA (7a ed.)
Walton, R., & O'Connell, S. (1994). Focus on Advanced English. Grammar Practice. Thomas Nelson and Sons.
Cita Chicago Style (17a ed.)
Walton, Richard, y Sue O'Connell. Focus on Advanced English. Grammar Practice. London: Thomas Nelson and Sons, 1994.
Cita MLA (9a ed.)
Walton, Richard, y Sue O'Connell. Focus on Advanced English. Grammar Practice. Thomas Nelson and Sons, 1994.
Precaución: Estas citas no son 100% exactas.