World Watch Institute. (2006). State of the world 2006, The challenge of global sustainability.
Chicago Edition CitationWorld Watch Institute. State of the World 2006, The Challenge of Global Sustainability. London, Earth Scan, 2006.
MLA Edition CitationWorld Watch Institute. State of the World 2006, The Challenge of Global Sustainability. 2006.
Warning: These citations may not always be 100% accurate.