http://www.theguardian.com/environment/2013/may/23/running-shoes-carbon-footprint
http://newsoffice.mit.edu/2013/footwear-carbon-footprint-0522
http://www.washingtonpost.com/natio...f4918c-da58-11e1-a3f5-b4e7667a8298_story.html
http://www.nytimes.com/2007/03/06/business/businessspecial2/07label-sub.html
http://newsoffice.mit.edu/2013/footwear-carbon-footprint-0522
http://www.washingtonpost.com/natio...f4918c-da58-11e1-a3f5-b4e7667a8298_story.html
http://www.nytimes.com/2007/03/06/business/businessspecial2/07label-sub.html