1. Abraham, R.G. & Vann, R.J. (1987). Strategies of two language learners: A case study. In A. Wenden & J. Rubin (Eds.), Learner strategies in language learning (pp. 85-102), Englewood Cliffs, NJ: Prentice Hall.
2. Bachman, L. (1990). Fundamental considerations in language testing. Oxford: Oxford University Press.
3. Brown, J.D. (1988). Understanding research in second language learning. Cambridge: Cambridge University Press.
4. Cohen, A.D. (1987). Using verbal reports in research on language learning. In C. Faerch & G. Kasper (Eds.), Introspection in second language research (pp. 82-95). Clevedon, UK: Multilingual Matters.
5. Ellis, R. (1994). The study of second language acquisition. London: Oxford University Press.