Cita APA (7a ed.)

Kirby, S., & Key, P. (1985). Penguin listerning skills: Teacher's book. Penguin.

Cita Chicago Style (17a ed.)

Kirby, Stephen, y Patty Key. Penguin Listerning Skills: Teacher's Book. Harmondsworth: Penguin, 1985.

Cita MLA (9a ed.)

Kirby, Stephen, y Patty Key. Penguin Listerning Skills: Teacher's Book. Penguin, 1985.