Richards, Michael D
John Wiley & Sons, 2014
Buku Teks SO
Wasson, Ellis
Wiley-Blackwell, 2010
Buku Teks SO
White, Michele, (author.)
Routledge, 2015
Buku Teks SO
Equal Opportunities Commission
Her Majesty's Stationery Office, 1987
Buku Referensi
Arnstein, Walter L.
Head, 1983
Buku Teks SO