APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

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

MLA (9th ed.) Citation

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