Jefferson, Michael
Cavendish Publishing , 1994
Buku Teks
Daniels, Kathy
Chartered Institute of Personnel and Development, 2012
Buku Teks
Whincup, Michael H., 1929-
Butterworth-Heinemann, 1995
Buku Teks
Painter, Richard W.
Pluto Press, 1993
Buku Teks
Keenan, Denis T.
Pitman, 1970
Buku Teks