Cadle, Patrick
UNDP, 2008
Buku Teks SO
Dilenschneider, Robert L.
American Management Association, 2010
eBooks
edited by Philip Lesly
Prentice-Hall, 1955
Buku Teks SO
edited by Walter Carlsnaes, Thomas Risse and Beth A. Simmons
Sage, 2013
Buku Teks SO
Yoder, Dale
McGraw-Hill, 1958
Buku Teks