APA (7e ed.) Bronvermelding

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

Chicago (17e ed.) Bronvermelding

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

MLA (8e ed.) Bronvermelding

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