Mills, Daniel Quinn, author
McGraw-Hill Irwin, 1982
Buku Teks
Dabscheck, Braham
GeorgeAllen & Unwin , 1981
Buku Teks
edited by Max S. Wortman
Allyn and Bacon , 1970
Buku Teks
Reis, Matthew, author
American Management Association, 2010
eBooks
French, Wendell L., author
Harper & Row, 1985.
Buku Teks