Citazione Stile APA (7a Edizione)

Langan, J., & Butcher, P. A. (2001). English Skills (séptima edición.). McGraw - Hill Companies, Inc.

Citazione stile Chigago Style (17a edizione)

Langan, John, e Phillip A. Butcher. English Skills. séptima edición. New York, NY: McGraw - Hill Companies, Inc, 2001.

Citatione MLA (9a ed.)

Langan, John, e Phillip A. Butcher. English Skills. séptima edición. McGraw - Hill Companies, Inc, 2001.