1. The impact hazard;Morrison,1994
2. The investigation of natural global catastrophes;Hempsell;Journal of the British Interplanetary Society,2004
3. Probability of death on UK roads is quoted as 1/200 in “The Highway Code” the Stationary Office.
4. Our Final Hour;Rees,2003
5. The potential for space intervention in global catastrophes;Hempsell;Journal of the British Interplanetary Society,2004