Richards, Michael D
John Wiley & Sons, 2014
Buku Teks
Wasson, Ellis
Wiley-Blackwell, 2010
Buku Teks
White, Michele, (author.)
Routledge, 2015
Buku Teks
Equal Opportunities Commission
Her Majesty's Stationery Office, 1987
Buku Referensi
edited by Astrik L. Gabriel
Mediaeval Institute, University of Notre Dame, 1974
Buku Teks