Citazione Stile APA (7a Edizione)

Percil, J., & Gray, J. (1988). Prospects: An advanced course teacher's book. Penguin Books.

Citazione stile Chigago Style (17a edizione)

Percil, John, e Joanna Gray. Prospects: An Advanced Course Teacher's Book. London: Penguin Books, 1988.

Citatione MLA (9a ed.)

Percil, John, e Joanna Gray. Prospects: An Advanced Course Teacher's Book. Penguin Books, 1988.