U.S. Goverment, 2003
Buku Teks
United States Department of State, 1991
Buku Teks
Steinberg, Sheldon S.
Rosda Jayaputra, 1998
Buku Teks
Reisman, George
Caroline House Publishers, 1979
Buku Teks
edited by Roy A. Grisham, Jr., Paul D. McConaughy
WM. H. Wise, 1966
Buku Referensi