Cruse, Alan, author
Oxford University Press, 2004
Buku Teks
Trudgill, Peter, author
Penguin, 1995
Buku Teks
Montgomery, Martin, author
Routledge, Taylor & Francis Group, 2008
Buku Teks
Montgomery, Martin, author
Routledge , 1996
Buku Teks
Montgomery, Martin, author
Routledge , 1993
Buku Teks