1. US Environmental Protection Agency Overview of Greenhouse Gases http://www.epa.gov/climatechange/ghgemissions/gases/co2.html
2. MASBI a Sustainable Future for Aviation http://www.masbi.org/content/assets/MASBI_Report.pdf
3. Administration USEI Cellulosic biofuels begin to flow but in lower volumes than foreseen by statutory targets 2013 http://www.eia.gov/todayinenergy/detail.cfm?id=10131