1. Finney,B. and Jones,E.M. (ed.): Interstellar Migration and the Human Experience. University of California Press, 1985. 2. Hart,M.H.: An Explanation for the Absence of Extraterrestrials on Earth. Quarterly Journal of the Royal Astronomical Society, Vol. 16, 1975. Reprinted in: Zuckerman,B. and Hart,M.H. (ed.): Extraterrestrials: Where Are They? Pergamon Press, 1982, and Cambridge University Press, 1995. 3. Viewing,D.: Directly Interacting Extraterrestrial Technological Communities. Journal of the British Interplanetary Society, Vol. 28, 1975. 4. Crawford,I.A.: Interstellar travel: A review for astronomers. Quarterly Journal of the Royal Astronomical Society, Vol. 31, 1990. Reprinted with revisions in: Zuckerman,B. and Hart,M.H.(ed.): Extraterrestrials: Where Are They? Cambridge University Press, 1995. 5. Drake,F.: A Comparative Analysis of Space Colonisation Enterprises. In: The Search for Extraterrestrial Life: Recent Developments (Proceedings of the 112th Symposium of the IAU, 1984). D. Reidel Publishing Co., 1985. 6. Drake,F. and Sobel,D.: Is Anyone Out There? Delacorte Press, 1991, and Pocket Books, 1994. 7. Kardashev,N.: Transmission of Information by Extraterrestrial Civilisations. (Soviet Astronomy, Vol. 8, 1964) 8. Kardashev,N.: On the Inevitability and Possible Structures of Supercivilisations. In: The Search for Extraterrestrial Life: Recent Developments (Proceedings of the 112th Symposium of the IAU, 1984). D. Reidel Publishing Co., 1985. 9. Finney,B.: Voyagers into ocean space. In: Finney,B. and Jones,E.M. (ed.): Interstellar Migration and the Human Experience. University of California Press, 1985. 10. Jones,E.M.: Estimates of Expansion Timescales. In: Zuckerman,B. and Hart,M.H. (ed.): Extraterrestrials: Where Are They? Cambridge University Press, 1995. 11. Finney,B.: Exponential expansion: Galactic destiny or technological hubris? In: The Search for Extraterrestrial Life: Recent Developments (Proceedings of the 112th Symposium of the IAU, 1984). D. Reidel Publishing Co., 1985. 12. Kecskes,Cs.: The Possibility of Finding Traces of Extraterrestrial Intelligence on Asteroids. Journal of the British Interplanetary Society, Vol. 51, May 1998. 13. Tang,T. and Chang,G.: Classification of Extraterrestrial Civilisations. Quarterly Journal of the Royal Astronomical Society, Vol. 32, 1991. 14. Sepkoski,J.J.Jr.: Some implications of mass extinction for the evolution of complex life. In: The Search for Extraterrestrial Life: Recent Developments (Proceedings of the 112th Symposium of the IAU, 1984). D. Reidel Publishing Co., 1985. 15. O'Neill,G.K.: The Colonisation of Space. Physics Today, September 1974. 16. Ball,J.A.: Extraterrestrial intelligence: Where is everybody? In: The Search for Extraterrestrial Life: Recent Developments. (Proceedings of the 112th Symposium of the IAU, 1984). D. Reidel Publishing Co., 1985. 17. Couch,H., Auman,J. and Falvey,T.: Advanced Regenerative Life Support for Space Exploration. In: Behrend,A., MacElroy,R. and Reysa,R. (ed.): Regenerative Life Support Systems and Processes. Society of Automotive Engineers, 1991. 18. Tri,T., Brown,M., Ewert,M., Foerg,S. and McKinley,M.: Regenerative Life Support Systems Test Bed Development at NASA - Johnson Space Center. In: Behrend,A., MacElroy,R. and Reysa,R. (ed.): Regenerative Life Support Systems and Processes. Society of Automotive Engineers, 1991. 19. Senior,C.L.: Lunar Oxygen Production by Pyrolysis. In: Lewis,J.S., Matthews,M.S. and Guerrieri,M.L.(ed.): Resources of Near-Earth Space. University of Arizona Press, Tucson, 1993. 20. Freitas,R.A. (ed.): Advanced Automation for Space Missions. NASA, CP-2255, 1980. 21. Deschamps,L. and Glaser,P.: Prospects offered by electromagnetic launchers for launching payloads into orbit. Space Technology, Vol. 11, No. 1, 1991. 22. Brophy,J.R.: A segmented ion engine design for solar electric propulsion systems. Space Technology, Vol. 14, No. 1, 1994. 23. Feldman,W.C., Maurice,S., Binder,A.B., Barraclough,B.L., Elphic,R.C. and Lawrence,D.J.: Fluxes of Fast and Epithermal Neutrons from Lunar Prospector, Evidence for Water Ice at the Lunar Poles. Science, September 4, 1998. 24. O'Neill,G.K.: The High Frontier. William Morrow and Co., New York, 1976. 25. Rampino,M. and Haggerty,B.: Extraterrestrial impacts and mass extinctions of life. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 26. Adushkin,V. and Nemchinov,I.: Consequences of impacts of cosmic bodies on the surface of the Earth. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 27. Rabinowitz,D., Bowell,E., Shoemaker,E. and Muinonen,K.: The population of Earth-crossing asteroids. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 28. Glaser,P.: Power from Space - an Approach to Achieve the Development of Space Resources. In: Space Manufacturing 5. (Proceedings of the 7th Princeton/AIAA/SSI Conference). American Institute of Aeronautics and Astronautics, 1985. 29. Johnson-Freese,J. and Handberg,R.: Space, the Dormant Frontier. Praeger Publishers, Westport, 1997. 30. Schneider,S.H. and Thompson,S.L.: Simulating the climatic effects of nuclear war. Nature, Vol. 333, 19 May, 1988. 31. Toon,O.B., Zahnle,K., Turco,R. and Covey,C.: Environmental perturbations caused by asteroid impacts. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 32. Ahrens,T.J. and Harris,A.W.: Deflection and fragmentation of near-Earth asteroids. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 33. Harris,A.W., Canavan,G.H., Sagan,C. and Ostro,S.J.: The deflection dilemma: use versus misuse of technologies for avoiding interplanetary collision hazards. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 34. Bowell,E. and Muinonen,K.: Earth-crossing asteroids and comets: groundbased search strategies. In: Gehrels,T.(ed.): Hazards due to comets and asteroids. University of Arizona Press, Tucson, 1994. 35. Kuck,D.L.: Near-Earth Extraterrestrial Resources. In: Space Manufacturing 3. (Proceedings of the 4th Princeton/AIAA/SSI Conference). American Institute of Aeronautics and Astronautics, 1979. 36. Lewis,J.S. and Lewis,R.A.: Space Resources. Columbia University Press, New York, 1987. 37. Tillotson,B.J.: Work in Progress on the Design of Solar Power Satellites from Lunar Materials. In: Space Manufacturing 5. (Proceedings of the 7th Princeton/AIAA/SSI Conference). American Institute of Aeronautics and Astronautics, 1985.