1. Overview of NASA Electrified Aircraft Propulsion (EAP) Research for Large Subsonic Transports
2. Bradley, M. K., and Droney, C. K. “Subsonic ultra green aircraft research,” Contractor Report NASA/CR-2011-216847, NASA Langley Research Center, Hampton, VA, 2011.
3. Bradley, M. K., and Droney, C. K. “Subsonic Ultra Green Aircraft Research Phase II: Hybrid Electric Design Exploration,” Contractor Report NASA/CR-2015-218704/Volume II, NASA Langley Research Center, Hampton, VA, 2015.
4. Parallel Hybrid Gas-Electric Geared Turbofan Engine Conceptual Design and Benefits Analysis