Cita APA (7a ed.)

Walker, M. (1989). ESL: Activity book. Addison-Wesley Publishing Company.

Cita Chicago Style (17a ed.)

Walker, Michael. ESL: Activity Book. New York, EUA: Addison-Wesley Publishing Company, 1989.

Cita MLA (9a ed.)

Walker, Michael. ESL: Activity Book. Addison-Wesley Publishing Company, 1989.