Dominik Rutz and Rainer Jansen (February 2007). "BioFuel Technology Handbook"(PDF). WIP Renewable Energies. Archived(PDF) from the original on 20 August 2008. Retrieved 2008-09-01. See definition in Glossary and Abbreviations
Alternative Fuels and Advanced Vehicles Data Center. "Natural Gas Vehicles". US Department of Energy. Archived from the original on 1 September 2008. Retrieved 2008-09-01.
"Glossary"(PDF). Biofuel Marketplace Project. Archived from the original(PDF) on 2012-09-15. Retrieved 2014-12-21. See Glossary for definition of Bi-fuel Vehicle
Dominik Rutz and Rainer Jansen (February 2007). "BioFuel Technology Handbook"(PDF). WIP Renewable Energies. Archived(PDF) from the original on 20 August 2008. Retrieved 2008-09-01. See definition in Glossary and Abbreviations
"Glossary". Biofuel Marketplace. Archived from the original on December 11, 2008. Retrieved 2008-09-01. See definition of FFV
Alternative Fuels and Advanced Vehicles Data Center. "Natural Gas Vehicles". US Department of Energy. Archived from the original on 1 September 2008. Retrieved 2008-09-01.
Agência AutoInforme (2006-06-19). "Siena Tetrafuel vai custar R$ 41,9 mil" (in Portuguese). WebMotor. Archived from the original on 2008-12-10. Retrieved 2008-08-14. The article argues that even though Fiat called it tetra fuel, it actually runs on three fuels: natural gas, ethanol, and gasoline.
Agência AutoInforme (2006-06-19). "Siena Tetrafuel vai custar R$ 41,9 mil" (in Portuguese). WebMotor. Archived from the original on 2008-12-10. Retrieved 2008-08-14. The article argues that even though Fiat called it tetra fuel, it actually runs on three fuels: natural gas, ethanol, and gasoline.
"Glossary"(PDF). Biofuel Marketplace Project. Archived from the original(PDF) on 2012-09-15. Retrieved 2014-12-21. See Glossary for definition of Bi-fuel Vehicle