Woodhall, Victoria
Hodder & Stoughton, 1992
Buku Teks
Donaldson, Bruce, author
Routledge, 2006
Buku Teks
Wessels, Dieter, author
Macmillan, 1992
Buku Teks
Ebert, Ronald J., author
Prentice-Hall, 1998
Buku Teks
Bradley, Teresa, author
John Wiley & Sons, 2002
Buku Teks