Hickman, Ian, author
Newnes, 1995
Buku Teks
Volkema, Roger, author
American Management Association;, 2006
eBooks
Green, James H., author
McGraw-Hill, 1984
Buku Teks
Bevington, David, author
BlackWell Publishing, 2006
Buku Teks
Harrington, Harold David, author
Swallow Press, 1979
Buku Teks