1. US Environmental Protection Agency, in Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2012 (2014).
http://www.epa.gov/climatechange/emissions/usinventoryreport.html%3E
2. US Department of Energy, National Hydrogen Energy Roadmap (2002).
http://www.hydrogen.energy.gov/pdfs/national_h2_roadmap.pdf
3. US Department of Energy, Office of Energy Efficiency and Renewable Energy and the Freedom CAR and Fuel Partnership, Technical System Targets: Onboard Hydrogen Storage for Light-Duty Fuel Cell Vehicles (2009).
http://energy.gov/sites/prod/files/2015/01/f19/fcto_myrdd_table_onboard_h2_storage_systems_doe_targets_ldv.pdf
4. US Department of Energy, in Office of Energy Efficiency and Renewable Energy and the Freedom CAR and Fuel Partnership, Targets for Onboard Hydrogen Storage Systems for Light-Duty Vehicles, US Department of Energy (2009).
http://energy.gov/sites/prod/files/2014/03/f11/targets_onboard_hydro_storage_explanation.pdf
5. US Department of Energy, Office of Energy Efficiency and Renewable Energy, National Hydrogen Storage Project. (2015).
http://energy.gov/eere/fuelcells/national-hydrogen-storage-project