Albright, Mary
Prentice-Hall, 1997
Buku Teks
Katcher, Bruce Leslie, author
American Management Association, 2007
eBooks
Planty, Earl G.
Ronald Press Company, 1948
Buku Teks
Dowling, William F., author
McGraw-Hill Kogakusha, 1978
Buku Teks
Harvard Business School Press, 2004
Buku Teks