* Astronomy

"X-15: Extending the Frontiers of Flight" by Dennis R. Jenkins
The X-15 was the ultimate "X" vehicle. Built in the 1950s, she became the fastest and highest-flying winged aircraft of its time. During 199 flights from 1959 through 1968, she collected data about hypersonic flight that was invaluable to aeronautics and to developers of the space shuttle. This book describes the genesis of the program, the design and construction of the aircraft, years of research flights and the experiments that flew aboard them.

+ X-15: Extending the Frontiers of Flight [Kindle, Kindle DX] 
NOTE: CTRL-click to save file (Mac and PC).

+ X-15: Extending the Frontiers of Flight [Sony Reader] 
NOTE: Ctrl-Click to save file (Mac), or for the PC, left-click to open file (it takes a moment to load) and then save file to your desktop.

Source