Pile, Steve, author
Routledge, 1996
Buku Teks
Goodall, Brian, author
Penguin Books, 1987
Buku Referensi
edited by R.J. Johnston, Derek Gregory, Geraldine Pratt, Michael Watts
Blackwell Publishing, 2000
Buku Referensi
edited by Julie Cidell and David Prytherch
Routledge, 2015
Buku Teks
Peter Daniels [and others]
Prentice-Hall, 2001
Buku Teks