William Ury's Abraham Path (http://abrahampath.org/) has been very influencial in the formation of the Interfaith Green School.  William Ury was the co-founder of the Harvard Program on Negotiation.  He helped found the International Negotiation Network.  He is the co-author of Getting to Yes with Roger Disher, which set out the method of principled negotiation and established the idea of the Best Alternative to a Negotiated Agreement within negotiation theory.