1Gass, S. M. & Selinker, L. 1994. Second language acquisition: An introductory course. Hillsdale, New Jersey: Lawrence Erlbaum.
2Gleason, J. B. & Ramer, N. B. (eds.). 1998. Psycholinguistics. Fort Worth: Harcourt Brace College Publishers.
3Kachru, B. B. 1990. World English and applied linguistics. WORLD ENGLISH. 9, 3- 20.
4Lenneberg, E. 1967. Biological foundations of language. New York : Wiley.
5McLaughlin, B. 1982. Second language learning and bilingualism in children and adults. In S. Rosenberg (ed.), Handbook of applied psycholinguistics: Major thrusts of research and theory. Hillsdale, New Jersey: Lawrence Erlbaum.
6Romaine, S. 1995. Bilingualism (Second Edition). Oxford, UK: Blackwell Publishers.
7Thompson, L. , Christian, D. , Stansfield, C.W. & Rhodes, N. 1990. Foreign language instruction in the United States. In A. M. Padilla, H. H. Fairchild & C. M. Valadez (eds.), Foreign language education: Issues and strategies. Newbury Park: SAGE.