1. Aijmer, K., Altenberg, B. (Eds.), 1991. English Corpus Linguistics: Studies in Honour of Jan Svartvik. Longman, London.
2. Biber, D., 1988. Variation Across Speech and Writing. Cambridge University Press, Cambridge.
3. Butler, C., 1990. Qualifications in Science: modal meanings in scientific text. In: Nash, W. (Ed.), The Writing Scholar. Sage Publications, London, pp. 137–170.
4. Crombie, W., 1985. Discourse and Language Learning: A Relational Approach to Syllabus Design. Oxford University Press, Oxford.
5. The pragmatics of doing language science: the warrant for large-corpus linguistics;de Beaugrande;Journal of Pragmatics,1996