Jackson, Susan E., author
South Westh Western College, 2000
Buku Teks
Stone, Thomas H
The Dryden Press, 1982
Buku Teks
Harvard Business School Press, 1998
Buku Teks
Gellerman, Saul W.
Penguin Book, 1974
Buku Teks
Scott, Walter Dill, author
McGraw-Hill, 1959
Buku Teks