X Planes 2... the Next Generation
X Planes, A History of the World's most Secret Planes and Missions
X Planes, Secret Planes and Secret Missions
X-15 Research Plane (NASA)
X-15, the NASA Mission Reports (with CD-ROM)
X-Fighters - USAF Experimental Fighters XP-59 to YF-23
X-Planes and Prototypes, From Nazi secret weapons to Warplanes of
X-Planes Crashes
X-Planes Photo Scrapbook
X-Planes, X-1 to X-29 (MCP/Specialty Press)
X-Planes, X-1 to X-29 (nd)
X-Planes, X-1 to X-31 (New revised edition)
X-Planes, X-1 to X-45
XF-18, de Roman van een Testpiloot