Brewster, Lawrence G.
Thomson wadsworth, 2004
Buku Teks
Judd, Dennis R.
Little, Brown, 1979
Buku Teks
Huntington, Samuel P.
The Belknap Press, 1981
Buku Teks
McCarthy, Eugene J., 1916-2005
Macmillan, 1962
Buku Teks
Epstein, Edwin M.
Prentice-Hall, 1969
Buku Teks