Wacks, Raymond, author
Oxford University Press, 2013
Buku Teks
Levy, Leonard W., author
Harper, 1963
Buku Teks
Beer, Lawrence Ward, 1932-
Kodansha International, 1984
Buku Teks
Steinby, Torsten, author
Government, 1971
Buku Teks
edited by Herman Wasserman
Routledge, 2013
Buku Teks