@article{zhai_frey_rouphail_goncalves_farias_2009, title={Comparison of flexible fuel vehicle and life-cycle fuel consumption and emissions of selected pollutants and greenhouse gases for ethanol 85 versus gasoline}, volume={59}, DOI={10.3155/1047-3289.59.8.912}, number={8}, journal={Journal of the Air & Waste Management Association}, author={Zhai, H. B. and Frey, H. C. and Rouphail, N. M. and Goncalves, G. A. and Farias, T. L.}, year={2009}, pages={912–924} }
 @article{zhai_frey_rouphail_2008, title={A vehicle-specific power approach to speed- and facility-specific emissions estimates for diesel transit buses}, volume={42}, DOI={10.1021/es800208d}, number={21}, journal={Environmental Science & Technology}, author={Zhai, H. B. and Frey, H. C. and Rouphail, N. M.}, year={2008}, pages={7985–7991} }
 @article{frey_rouphail_zhai_2008, title={Link-based emission factors for heavy-duty diesel trucks based an real-world data}, number={2058}, journal={Transportation Research Record}, author={Frey, H. C. and Rouphail, N. M. and Zhai, H. B.}, year={2008}, pages={23–32} }
 @article{frey_rouphail_zhai_farias_goncalves_2007, title={Comparing real-world fuel consumption for diesel- and hydrogen-fueled transit buses and implication for emissions}, volume={12}, DOI={10.1016/j.trd.2007.03.003}, number={4}, journal={Transportation Research. Part D, Transport and Environment}, author={Frey, H. C. and Rouphail, N. M. and Zhai, H. B. and Farias, T. L. and Goncalves, G. A.}, year={2007}, pages={281–291} }