Risjord, Norman K., author
Prentice-Hall, 1985
Buku Teks
Williams, T. Harry, author
Alfred A. Knopf, 1963
Buku Teks
Beard, Charles A., author
New Home Library, 1944
Buku Teks
Lippincott, Isaac, author
Appleton Century Croffs, 1933
Buku Teks
introduction by Edward G. Smith
Barnes & Noble, 1966
Buku Teks