Fogel, Robert William
Johns Hopkins Press, 1964
Buku Teks
McCamy, James L.
Alfred A. Knopf, 1952
Buku Teks
Kennan, George F., 1904-
Princeton University Press , 1954
Buku Teks
McCormick, James M.
Thomson, 2005
Buku Teks
Herrick, Christopher
Longman, 2003
Buku Teks