1[1]Anderson,L.& Trudgill, P., 1990. Bad Language. Oxford:Basil Blackwell.
2[2]Akmjian,A., Deners,R., Hamish,R., 1988. 2nd ed. Linguistics. Lyons, J., 1981. Language and Linguistics. Cambrildge;Cambridge Wolfram, W., 1991. Dialects and American English. Washington: Prentice - Hall, University Press