Cadle, Patrick
UNDP, 2008
Buku Teks
edited by Walter Carlsnaes, Thomas Risse and Beth A. Simmons
Sage, 2013
Buku Teks
Dilenschneider, Robert L.
American Management Association, 2010
eBooks
edited by Philip Lesly
Prentice-Hall, 1955
Buku Teks
Macnamara, Jim
Prentice Hall Australia, 1996
Buku Referensi