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2. A report of working group of the intergovernmental panel on climate change. 〈http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf〉.
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4. Emission norms, society of Indian automobile manufacturers. 〈http://www.siamindia.com/scripts/emission-standards.aspx〉.
5. Peak oil theory. 〈http://www.ucs.mun.ca/~oilpower/documents/Peakoil2-1.doc.pdf〉.