Beshara, Tony
Amacom, 2011
Buku Teks SO
Siegel, Liza
American Management Association, 2006
eBooks
Livoti, Carol
American Management Association, 2009
eBooks
Kaplan, Robert S.
Harvard Business Review Press, 2015
Buku Teks SO
Kelly, Francis J.
Warner Book, 1986.
Buku Teks SO