1. United Nations Environment Programme PO Box 30552 Nairobi Kenya published in 2000 web site: , ISBN: 92-807-1888-6.
2. Summary for Policy Makers;Edenhofer,2011
3. Carbon Dioxide Recovery and utilization;Aresta,2010
4. .
5. ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/co2_annmean_mlo.txt.