References
Fogg, Martyn J. Terraforming; Engineering Planetary Environments. Warrendale, PA 1995.
Gilmour,Iain., and Mark A. Sephton. An Introduction to Astrobiology. New York: Cambridge University Press, 2003.
NASa Astrobiology Page. NASA. December 2005. 30 NOv. 2005 <http://astrobiology.arc.nasa.gov/>.
European Space agency. ESA. December 2005. 5 DEC. 2005http://www.esa.int/esaCP/index.html