Cita APA

Kirby, S., & Key, P. (1989). Penguin elementary speaking skills: Student's book. London: Penguin Books.

Citación estilo Chicago

Kirby, Stephen, and Patty Key. Penguin Elementary Speaking Skills: Student's Book. London: Penguin Books, 1989.

Cita MLA

Kirby, Stephen, and Patty Key. Penguin Elementary Speaking Skills: Student's Book. London: Penguin Books, 1989.