Harley, B. (1990). The Development of second language proficiency. Cambridge University Press.
Chicago Style (17th ed.) CitationHarley, Birgit. The Development of Second Language Proficiency. Cambridge University Press, 1990.
MLA (8th ed.) CitationHarley, Birgit. The Development of Second Language Proficiency. Cambridge University Press, 1990.
Warning: These citations may not always be 100% accurate.