1. UN Commission on Sustainable Development (UNCSD) (2006) Indicators of sustainable development: guidelines and methodologies third edition. http://www.un.org/esa/sustdev/natlinfo/indicators/methodology_sheets.pdf . Accessed 27 Sept 2010
2. Parris TM, Kates RW (2003) Characterizing and measuring sustainable development. Annu Rev Environ Resour 28:559–586
3. Schweimer G, Levin M (2000) Life cycle inventory for the golf a4. Volkswagen AG, Wolfsburg. http://www.volkswagen-environment.de/ . Accessed 17 Sep 2010
4. Brealey R, Myers SC (2003) Principles of corporate finance. 7th edn (Int Ed) McGraw-Hill, New York
5. Global Reporting Initiative (GRI) (2006) Sustainability reporting guidelines, Version 3.0. http://www.globalreporting.org/NR/rdonlyres/ED9E9B36-AB54-4DE1-BFF2-5F735235CA44/0/G3_GuidelinesENU.pdf . Accessed 17 Sep 2010