Goodall, Brian, author
Penguin Books, 1987
Buku Referensi
edited by R.J. Johnston, Derek Gregory, Geraldine Pratt, Michael Watts
Blackwell Publishing, 2000
Buku Referensi
Whittow, John B., author
Allen Lane, 1984
Buku Referensi
Moore, W.G.
London : Penguin Books, 1984,
Buku Referensi
Mayhew, Susan, author
Oxford University Press, 1992
Buku Referensi