Aruego, Jose M., author
University Book Supply, 1975
Buku Teks
Bromage, Arthur W.
Appleton-Century-Crofts,Inc., 1950
Buku Teks
Appleby, Paul H., author
Louisiana State University Press, 1952
Buku Teks
U.S. Goverment, 2003
Buku Teks
Welch, Susan author
Wadsworth/Cengage learning, 2010
Buku Teks