Tade Matthias Spranger
Springer, 2012
eBooks
Pollit, Christopher
Oxford University press, 2000
Buku Teks
Anna Galluzzi
Chandos , 2014
eBooks
Mark Bovens, Paul't Hart, B. Guy Peters
Edward Elgar Publishing, Inc, 2001
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Watson, Adam
Routledge, 1992
Buku Teks