Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (9th ed.)

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