1. Department for Food and Rural Affairs: Climate Change Act 2008. DEFRA. 2008, London, United Kingdom
2. World Medical Association: World Medical Association Declaration of Helsinki. WMA General Assembly. 1964, Helsinki, Finland.
http://ohsr.od.nih.gov/guidelines/helsinki.html
3. World Business Council for Sustainable Development: Calculations Tools. 2005.
http://www.ghgprotocol.org/
4. Department for Food and Rural Affairs: 2009 Guidelines to Defra/DECC's GHG Conversion Factors for Company Reporting. DEFRA. 2009.
http://www.defra.gov.uk/environment/business/reporting/pdf/20090928-guidelines-ghg-conversion-factors.pdf
5. Intergovernmental Panel on Climate Change: IPCC Guidelines for National Greenhouse Gas Inventories: Reference Manual. IPCC. 2006.
http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/0_Overview/V0_0_Cover.pdf