Trudgill, Peter, author
Penguin, 1995
Buku Teks
Cambridge University Press, 2010
eBooks
Kern, Richard, author
Cambridge University Press, 2015
eBooks
Carter, Ronald, author
Routledge, 2004
Buku Teks
Trudgill, Peter, author
Departemen Pendidikan dan Kebudayaan , 1978
Buku Teks