7Austin, J. L. 1962. How to Do Things with Words. Oxford: Clarendon Press.
8Biber, D. 1988. Variation across Speech and Writing. Cam- bridge: Cambridge University Press.
9Brown, P. & S. Levinson. 1987. Polite~ss: Some Univer- sals in Language Usage. Cambridge: Cambridge Universi- ty Press.
10Chafe, W. 1982. Integration and involvement in speaking, writing, and oral literature. In D. Tannen (ed.). Spoken and Written Language: Exploring Orality and Literacy. Norwood : Ablex, 35 - 53.