http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
WMO WDCGG data report : part B (other atmospheric gases) : gaw data volume IV-greenhouse gases and other atmospheric gases
The Japan Meteorological agency in cooperation with the world Meteorological Organization
World Meteorological Organization : Global Atmosphere Watch : World Data Centre for Greenhouse Gases