1. BFPA (British Fluid Power Association) . 2003 . Guidelines on hydraulic fluids. British Fluid Power Association, Chipping Norton, UK: BFPA.
2. BRDTA (Biomass Research and Development Technical Advisory Committee) . 2002 . Vision for bio-energy and biobased products in the United States. (www.bioproducts-bioenergy.gov/pdfs/Bio-Vision_03_Web.pdf). Accessed 21 July 2003.
3. Industrial Ecology and Competitiveness.
4. J. Fiksel, J. McDaniel, and D. Spitzley., 1998 . Measuring product sustainability . Journal of Sustainable Product DesignIssue 6 July 1998: 7 -19 .