Graber, Doris A.
Congressional Quarterly Press, 1980
Buku Teks
Williams, Patrick, 1930-
Greenwood Press, 1978
Buku Teks
Hammitt, William E.
John Wiley & Sons, 1987
Buku Teks
Alison Alexander, Jarice Hanson, editor
McGraw-Hill/Dushkin, 2001
Buku Teks
[compiled by] Warren K. Agee, Phillip H. Ault, Edwin Emery
Harper & Row Publishers, 1986
Buku Teks