1. Fuel cells for transportation
2. Gas Research Institute, Light Duty Vehicle Full Fuel Emissions Analysis, Gas Research Institute, National Gas Vehicles Products Group, GRI-93/0472, 1994.
3. NRC, Rethinking The Ozone Problem In Urban And Regional Air Pollution, National Academy Press, Washington, DC, 1991.
4. Daimler Benz, Booklet: NECAR II — Fahren ohne Emissionen, 1996.