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2. IUP, Institute für Umweltphysik, http://www.flickr.com/photos/41766005@N06/4042373874/
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4. Pacala Steve, Princeton University Centre for Energy and Environmental Studies (PU-CEES), as reported by Robert Socolow at CLAIRE Convention, Politecnico di Torino, Pra Catinat, May 2013.
5. Socolow Robert, Princeton University Centre for Energy and Environmental Studies (PU-CEES), CLAIRE Convention, Politecnico di Torino, Pra Catinat, May 2013.