Wiki (http://en.wikipedia.org/wiki/Gaia_hypothesis)
The Gaia Hypothesis (http://www.physicalgeography.net/fundamentals/5d.html)
Patterns, Flows, and Interrelationship (http://www.mollyyoungbrown.com/systems_article.htm)
The Earth as a System (http://www.isss.org/primer/earthsys.htm)