Simpson, Colin D.
Prentice-Hall, 1996
Buku Teks
Kissell, Thomas E.
Prentice Hall International, 1997
Buku Teks
Gilmer, B. von Haller (Beverly von Haller), 1909-1994
McGraw-Hill, 1966
Buku Teks
McCormick, Ernest James
Prentice-Hall, 1980
Buku Teks
Toynbee, Arnold J.
The Beacon Press , 1961
Buku Teks