Gorman, Michael
American Library Association, 2003
Buku Teks
Warner, Langdon
Harvard University Press, 1952
Buku Teks
Koupelis, Theo
Jones & Bartlett learning, 2011
Buku Teks
Steinby, Torsten
Government, 1971
Buku Teks
Koupelis, Theo
Jones and Bartlett, 2011
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