Tech debt article: http://swreflections.blogspot.com.au/2012/02/technical-debt-how-much-is-it-really.html
Capers Jones PDF: http://sqgne.org/presentations/2011-12/Jones-Sep-2011.pdf
Capers Jones facts and figures: http://allankelly.blogspot.com.au/2011/02/more-facts-and-figures-from-capers.html
