Cita APA (7th ed.)

Krashen, S. D. (1981). Second language acquisition and second language learning. Pergamon Press.

Cita Chicago (17th ed.)

Krashen, Stephen D. Second Language Acquisition and Second Language Learning. Oxford: Pergamon Press, 1981.

Cita MLA (9th ed.)

Krashen, Stephen D. Second Language Acquisition and Second Language Learning. Pergamon Press, 1981.