Hogerth, Robin M.
John Wiley & Sons, 1979
Buku Teks
Reynolds, John I.
International Labour Office, 1980
Buku Teks
Clardy, Alan, author
Amacom, 2012
Buku Teks
Clardy, Alan, author
American Management Association, 2012
eBooks
Porter, Lyman W., author
McGraw-Hill, 1988
Buku Teks