Josephson, Matthew, author
Houghton Mifflin, 1969
Buku Teks
Cornwall, John, author
Wakefield Press, 1989
Buku Teks
Kongressional Quarterly, 2000
Buku Teks
McClelland, James, author
Viking, 1989
Buku Teks
Moser, Charles A., author
Caroline House, 1979
Buku Teks