Cita APA

Kirby,Stephen, & Key, P. (1985). Penguin listening skills: Student's book. New York: Penguin books.

Chicago Style Citation

Kirby,Stephen, i Patty Key. Penguin Listening Skills: Student's Book. New York: Penguin books, 1985.

Cita MLA

Kirby,Stephen, i Patty Key. Penguin Listening Skills: Student's Book. New York: Penguin books, 1985.