1. Bradley, M. K., and Droney, C. K. “Subsonic Ultra Green Aircraft Research: Phase I Final Report,” Contractor Report NASA/CR-2011-216847, NASA Langley Research Center, Hampton, VA, April 2011.
2. Bradley, M. K., and Droney, C. K. “Subsonic Ultra Green Aircraft Research Phase II: N+ 4 Advanced Concept Development,” Contractor Report NASA/CR-2012-217556, NASA Langley Research Center, Hampton, VA, May 2012.