1. Gallant R. Journey to Tunguska. Sky Telescope 1994, p. 38–43.
2. Carusi A, Gehrels T, Heflin EF, Marsden BG, Russell KS, Shoemaker CS, Shoemaker EM, Steel DI. Near-earth objects: present search programs. Hazards due to comets and asteroids. Tuscon, Arizona: The University of Arizona Press, 1994, p. 128–9.
3. A National Security Strategy For A New Century. The White House 1998, p. 25–6.
4. Morrison D, Chapman CR, Slovic P. The impact hazard. Hazards due to comets and asteroids. Tuscon, Arizona: The University of Arizona Press, 1994, p. 86.
5. Sky Search Finds 7 Dangerous Asteroids. Montgomery Advertiser, Associated Press, 13 July 1997.