1. CFC-11 and CFC-12 release estimates from AFEAS;Alternative Fluorocarbons Environmental Acceptability Study,1994
2. A historical reconstruction of carbon dioxide and methane emissions in the United States 1880–1980;Ayres,1994
3. Valuing environmental functions: tropical wetlands;Barbier;Land Economics,1994
4. British Geological Survey (various years) United Kingdom Mineral Statistics (British Geological Survey, Keyworth, Nottinghamshire)
5. Global Methane Emissions from Livestock and Poultry Manure;Casada,1990