Easton, David, author
John Wiley & Sons, 1965
Buku Teks
edited by David Ingram
Blackwell , 2002
Buku Teks
Beyme, Klaus Von, author
Springer, 2014
Buku Teks
edited by Robert E. Goodin, Charles Tilly
Oxford University Press, 2008
Buku Referensi
Howard, Tiffiany, author
Palgrave Macmillan, 2016
Buku Teks