edited by Cary L. Cooper, Ivan T. Robertson
John Wiley & Sons, 2000
Buku Teks
Steckle, Lynde C.
Happer , 1957
Buku Teks
Covey, Stephen R., author
A Fireside Book, 1989
Buku Teks
Strongman, Kenneth T., author
John Wiley & Sons, 2006
Buku Teks
Biehler, Robert F.
Houghton Miffiln, [date of publication not identified]
Buku Teks