1. EPA (U.S. Environmental Protection Agency) and National Highway Traffic and Safety Administration 2011 2017-2025 CAFE GHG Supplemental Rules http://www.epa.gov/otaq/climate/documents/420f12051.pdf
2. CARB (California Air Resources Board), California Environmental Protection Agency 2009 Low-Carbon Fuel Standard Program http://www.arb.ca.gov/fuels/lcfs/lcfs.htm
3. CARB 2008 The Zero Emission Vehicle Program - 2008 http://arbis.arb.ca.gov/msprog/zevprog/factsheets/2008zevfacts.pdf
4. ISO 2012 Hydrogen fuel - product specification - Part 2: Proton exchange membrane (PEM) fuel cell applications for road vehicles
5. DOE (U.S. Department of Energy) 2014 Production Case Studies www.hydrogen.energy.gov/h2a_prod_studies.html