1. Bates B Lennox A Swan G 2010 National Diet and Nutrition Survey: headline results from year 1 of the rolling programme (2008-2009) http://www.food.gov.uk/multimedia/pdfs/publication/ndnsreport0809.pdf
2. DEFRA (Department for Environment, Food and Rural Affairs) 2011a Indicator DD1: methane http://archive.defra.gov.uk/evidence/statistics/foodfarm/enviro/observatory/indicators/d/dd1_data.htm
3. DEFRA (Department for Environment, Food and Rural Affairs) 2011b Indicator DD2: nitrous oxide emissions http://archive.defra.gov.uk/evidence/statistics/foodfarm/enviro/observatory/indicators/d/dd2_data.htm
4. FAO (Food and Agriculture Organisation of the United Nations) 2009 The state of food and agriculture http://www.fao.org/docrep/012/i0680e/i0680e.pdf
5. Government Office for Science 2011 The future of food and farming: Challenges and choices for global sustainability report http://www.bis.gov.uk/assets/bispartners/foresight/docs/food-and-farming/11-546-future-of-food-and-farming-report.pdf