Slager, Williams
McGraw-Hill,
Buku Teks
King, Gareth, author
Routledge, 2005
Buku Teks
McArthur, Tom (Thomas Burns), author
Oxford University Press, 1983
Buku Teks
Tong, Keith S. T., author
Routledge, 1994
Buku Teks
Swan, Michael, author
Cambridge University Press, 1992
Buku Teks