Bowen, John R., author
Pearson, 2005
Buku Teks
Bowie, Fiona, author
BlackWell Publishing, 2005
Buku Teks
Firth, Raymond, author
Routledge, 1996
Buku Teks
edited by Peter Clarke and Stewart Sutherland
Routledge, 1991
Buku Teks
Toynbee, Arnold J., author
Oxford University Press, 1956
Buku Teks