Massey, Doreen
Macmillan, 1995
Buku Teks
Farschtschian, Farsam
[Springer, ], 2012
eBooks
Wallace, Patricia M.
Cambridge University Press, 2004.
Buku Teks SO
Fadillah Putra
Universitas Brawijaya Press, 2012
Buku Teks
Bingham, Tony
ASTD press, 2010
Buku Teks