General Motors. Well-to-Wheel Energy Use and Greenhouse Gas Emissions of Advanced Fuel/Vehicle Systems-North American Analysis, Part 1. http://www.transportation.anl.gov/pdfs/TA/163.pdf. 2001
General Motors. Well-to-Wheel Energy Use and Greenhouse Gas Emissions of Advanced Fuel/Vehicle Systems-North American Analysis, Part 2. http://www.transportation.anl.gov/pdfs/TA/164.pdf. 2001
LBST. GM Well-to-Wheels Analysis of Energy Use and Greenhouse Gas Emissions of Advanced Fuels/Vehicles Systems. A European study. http://www.lbst.de/gm-wtw. 2002