Citazione Stile APA (7a Edizione)

Krashen, S. D., & Terrell, T. D. (1988). The natural approach: Language acquisition in the classroom. Prentice-Hall.

Citazione stile Chigago Style (17a edizione)

Krashen, Stephen D., e Tracy D. Terrell. The Natural Approach: Language Acquisition in the Classroom. New York: Prentice-Hall, 1988.

Citatione MLA (9a ed.)

Krashen, Stephen D., e Tracy D. Terrell. The Natural Approach: Language Acquisition in the Classroom. Prentice-Hall, 1988.