1. Electricity – Energy Explained;Energy Information Administration,2015
2. Energy Information Administration. U.S. Energy Facts – Energy Explained, Your Guide To Understanding Energy – n.d. https://www.eia.gov/energyexplained/?page=us_energy_home (accessed September 7, 2018).
3. Natural gas and biogas use in transit bus fleets – A technical, operational and environmental approach;Barbosa,2014
4. Optimization of performance and operational cost for a dual mode diesel-natural gas RCCI and diesel combustion engine;Ansari;Appl Energy,2018
5. ARPA-E. MOVE 2012. file:///D:/My Data/Publications/Submitted/Fuel Blends Paper/Sources/ARPA-E _ MOVE.html (accessed May 3, 2018).