Cost Control / How it Works in the Project

http://vig.pearsoned.co.uk/catalog/uploads/Ashworth%205e%20-%20Chapter%201%20web%20ready.pdf
http://projectpaths.blogspot.com/

Model

http://www.economistsdoitwithmodels.com/
http://www.econmodel.com/

Cost / Reduction / Using Six Sigma

http://economicswebinstitute.org/glossary/costs.htm
http://www.shumaonline.com/
http://sixsigmainformation.blogspot.com