Cox, C. Barry
Blackwell, [Date of publication not identified]
Buku Teks SO
Cox, C. Barry
John Wiley & Sons, 2010
Buku Teks SO
edited by A.A. Myers and P.S. Giller
Chapman & Hall, 1988
Buku Teks SO
Huggett, Richard John
Routledge, 1998
Buku Referensi
Mielke, H.W
Unwin Hyman, 1988
Buku Teks SO