DeGreene, Kenyon B., author
John Wiley, 1982
Buku Teks
Bolles, Dennis L., author
American Management Association, 2007
eBooks
Macmillan, 1971
Buku Teks
Scanlan, Burt
John Wiley & Sons, 1983
Buku Teks
Gerloff, Edwin A., author
McGraw-Hill, 1985
Buku Teks