Academy of Political Science, 2018
Majalah, Jurnal, Buletin
Jacobsen, Gertude Ann
Barnes & Noble, 1951
Buku Teks
by Carlton Clymer Rodee [and others]
McGraw-Hill, 1983
Buku Teks
Fowler, Robert Booth, author
Praeger, 1985
Buku Teks
edited by James C. Charlesworth
The Free Press, 1968
Buku Teks