Kirby,Stephen, & Key, P. (1985). Penguin listening skills: Student's book. New York: Penguin books.
Chicago Style aipamenaKirby,Stephen, và Patty Key. Penguin Listening Skills: Student's Book. New York: Penguin books, 1985.
MLA aipamenaKirby,Stephen, và Patty Key. Penguin Listening Skills: Student's Book. New York: Penguin books, 1985.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.