Witman, Shepherd Luther, 1906-, author
Littlefield, Adams, 1963
Buku Teks
U.S. Goverment, 2003
Buku Teks
Roberts, Robert North, author
Greenwood Press, 2001
Buku Teks
editor, Kathleen E. Hug; penerjemah, Sumantri Ar.
Office of International Infrmation Programs US Department of State, [date of publication not identified]
Buku Teks
Reisman, George, author
Caroline House Publishers, 1979
Buku Teks