1. Staff at the National Astronomy and Ionosphere Center, The Arecibo message of November, 1974, Icarus 26(4) (1975) 462–466.
2. R.H. Goddard, Report to Smithsonian Institution concerning further developments of the rocket method of investigating space, March 1920, in: E.C. Goddard (Ed.), The Papers of Robert H. Goddard, Vol. 1, McGraw-Hill, New York, 1970, pp. 413—428.
3. R.H. Goddard, Supplementary notes concerning “Report concerning further developments, March 1920,” August 27, 1929, in: E.C. Goddard (Ed.), The Papers of Robert H. Goddard, Vol. 1, McGraw-Hill, New York, 1970, pp. 428—430.
4. A message from Earth;Sagan;Science,1972
5. Murmurs of Earth: The Voyager Interstellar Record,1978