APA aipamena

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

Chicago Style aipamena

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

MLA aipamena

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