Keefe, William J.
The American legislative process congress and the state
Prentice-Hall, 1994
 Buku Teks
OConnor, Karen
American government
Addison Wesley Longman, 2001
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Rossiter, Clinton, 1917-1970
The American presidency
The American Library, 1960
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Welch, Susan
American government
Thomson, 2006
 Buku Teks
Leach, Richard H.
American federalism
W.W. Norton, 1970
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