Olmstead, Clifton E.
Prentice-Hall, 1960
Buku Teks SO
Goossens, Jerry
Arbeiderspers, 1998
Buku Teks
Imtip Pattajoti Suharto
National Archives of Thailand, 2001
Buku Teks
The Council of State Government, 1982
Buku Teks
Kuykendall, Ralph S.
Prentice-Hall, 1961
Buku Teks SO