Cho, Kit Sum, et al. “Towards Meeting the IATA-Agreed 1.5% Average Annual Fuel Efficiency Improvements Between 2010 and 2020: the Current Progress Being Made by U.S. Air Carriers”. Aviation, vol. 23, no. 4, Dec. 2019, pp. 123-32, https://doi.org/10.3846/aviation.2019.12019.