Barone, Michael, author
National Journal, 1992
Buku Referensi
Barone, Michael, author
National Journal, 1990
Buku Referensi
Althen, Gery, author
Intercultural Press, 2003
Buku Teks
Hombs, Mary Ellen
ABC-Clio, 1990
Buku Teks
Polsby, Nelson W., author
Charles Scribner's Sons, 1980
Buku Teks