Cita APA (7a ed.)

Krashen, S. D. (1985). Principles and practice in second language acquisition. Pergamon.

Cita Chicago Style (17a ed.)

Krashen, Stephen David. Principles and Practice in Second Language Acquisition. New York [etc.]: Pergamon, 1985.

Cita MLA (9a ed.)

Krashen, Stephen David. Principles and Practice in Second Language Acquisition. Pergamon, 1985.