1. Aitchison, Jean. 2002.Words in the Mind: An Introduction to the Mental Lexicon(3rd edition). Oxford: Blackwell Publishers.
2. Halliday, M. A. K. 1975.Learning How to Mean: Exploration in the Development of language. London: Edward Arnold.
3. Hindmarsh, Roland. 1980.Cambridge English Lexicon. Cambridge: Cambridge University Press.
4. Maeda, Aya. 2002. “A Discourse Analysis of Social Skill Objectives in Terms of English Language Curriculum.”Papers in Language, Thought and CultureVol. 8. Seisen University, Tokyo.
5. MEXT Japanese Ministry of Education, Culture, Sports, Science and Technology. 2001. www.mext.go.jp/english/statist/index.htm