editor, Robert Pritchard
Kluwer Law International, 1996
Buku Teks SO
Ministry of Communication and Information Technology, 2008
Buku Referensi
Mott, Graham
Pitman, 1997
Buku Teks
Stillman, Richard N.
Holt, Rinehart and Wilson, 1962
Buku Teks
Buku Teks