Moonman, Eric, author
Pan Books, 1971
Buku Teks
Hyland, Bruce, author
Gramedia Pustka Utama, 1996
Buku Teks
Harvard Business School Press, 2004
Buku Teks
Flagello, Jane R., author
American Management Association, 2009
eBooks
Haneberg, Lisa, author
American Society for Training & Development, 2007
eBooks