Davies, Ioan
Pall Mall Press, 1970
Buku Teks
The International Political Science Association, 2009
Buku Referensi
edited by David Ingram
Blackwell , 2002
Buku Teks
King, J. Charles
McGraw-Hill, 1973
Buku Teks
Moten, Abdul Rashid, author
Thomson, 2006
Buku Teks