Beard, Charles A.
New Home Library, 1944
Buku Teks
Myers, Gustavus
Random House, 1943
Buku Teks
Myers, Margaret G.
Columbia University Press , 1970
Buku Teks
Kemmerer, Donald L.
Littlefield, Adams, 1956
Buku Teks
Rae, John B.
Mc Graw-Hill Book Company, 1949
Buku Teks