Crockett, James Underwood
Time-Life Books, 1972
Buku Referensi
Agung Erwan Setyobudi
Universitas Indonesia, 2007
UI - Tesis Membership
Universitas Gunadarma, 1993
Buku Teks SO
Lang, Donna.
Clarkson Potter Publisher,
Buku Teks SO
Clarkson Potter Publisher, 1996
Buku Teks SO