1. American Society of Agricultural Engineers 2005 Manure production and characteristics. ASAE D384.2 http://extension.psu.edu/animals/dairy/nutrient-management/certified-dairy/tools/manure-prod-char-d384-2.pdf
2. California Air Resources Board 2015 California cap-and-trade program and Quebec cap-and-trade system, May 2015 joint auction #3, summary results report http://www.arb.ca.gov/cc/capandtrade/auction/may-2015/summary_results_report.pdf
3. Manure management: Implications for greenhouse gas emissions;Chadwick;Anim. Feed Sci. Technol.,2011