Holmes, Janet
Longman, 1993
Buku Teks
Mey, Jacob L., author
Blackwel, 1993
Buku Teks
Trudgill, Peter, author
Penguin, 1995
Buku Teks
edited by William C. McCormack, Stephen A. Wurm
Mouton , 1979
Buku Teks
Montgomery, Martin, author
Routledge, Taylor & Francis Group, 2008
Buku Teks