McLeod, John, author
McGraw-hill Open University press, 2012
Buku Teks
edited by Mark Bevir
SAGE , 2013
Buku Teks
Gramberger, Marc, author
OECD, 2001
Buku Teks
Rose, Richard, 1933-, author
Routledge, 2005
Buku Teks
edited by Michael Moran, Martin Rein, Robert E. Goodin
Oxford University Press, 2008
Buku Referensi