Παραπομπή σε μορφή APA (7η εκδ.)

Ontario Institute for Studies in Education & Harley, B. (1990). The Development of second language proficiency. Cambridge University Press.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Ontario Institute for Studies in Education και Birgit Harley. The Development of Second Language Proficiency. Cambridge ; New York: Cambridge University Press, 1990.

Παραπομπή σε μορφή MLA (8th εκδ.)

Ontario Institute for Studies in Education και Birgit Harley. The Development of Second Language Proficiency. Cambridge University Press, 1990.