Griffith, Martin
Routledge, 2002
Buku Teks
edited by Beth A. Simmons and Richard H. Steinberg
Cambridge University Press, 2006
Buku Teks
edited by Philip Lesly
Prentice-Hall, 1955
Buku Teks
Dilenschneider, Robert L.
American Management Association, 2010
eBooks
Satya Arinanto
UNDP, [date of publication no identified]
Buku Referensi