Steinbreder, John, author
Hungry Minds, Inc., 2001
Buku Teks
De Mente, Boye, author
Tuttle Publishing, 2008
Buku Teks
Langford, Beverly Y., author
American Management Association, 2005
eBooks
Nance, Virginia L., author
WM. C. Brown, 1966
Buku Teks
Jorgensen, Theodore P., author
American Institute of Physics, 1993
Buku Teks