Pinkerton, William J.
McGraw-Hill , 2003
Buku Teks
Horton, William
ASTD Press, 2001
Buku Teks
Zabel, William D.
William Morrow and Company, Inc., 1995
Buku Teks
International Engineering Consortium
International Engineering Consortium, 2005
eBooks
Browne, Harry
Arlington House , 1971
Buku Teks