To See the Unseen: A History of Planetary Radar Astronomy (NASA SP-4218, 1996) by Andrew J. Butrica is at http://history.nasa.gov/SP-4218/sp4218.htm online.
To See the Unseen: A History of Planetary Radar Astronomy (NASA SP-4218, 1996) by Andrew J. Butrica is at http://history.nasa.gov/SP-4218/sp4218.htm online.