Collier, John Greenwood
Cambridge University Press, 1987
Buku Teks
Henn, Harry, Alexander, John R
St.Paul,Minn : West publishing Co, 1983,
Buku Referensi
Hay, Peter
West Publishing, 1994
Buku Teks
Montesquieu, Charles de Secondat,1689-1755
Hafner Press, 1949
Buku Teks SO
Ehrenzweig, Albert A.
West Publishing, 1959
Buku Teks