1. K. Denning, Ten Thousand Revolutions: Conjectures about Civilizations, Paper for session, SETI II: Interdisciplinary Aspects, International Astronautical Congress, Valencia, Spain, October 2006.
2. K. Denning, ‘L’ on Earth, IAC-05-A4.2.03, Paper for session, SETI II: Interdisciplinary Aspects, International Astronautical Congress, Fukuoka, Japan, October 2005. International Astronautical Congress online archive. OR see Kathryn Denning, ‘L’ on Earth, In: Douglas Vakoch, Albert Harrison (Eds.), Culture in the Cosmos: Extraterrestrial Life and Society, Berghahn Press, New York/Oxford, Forthcoming.
3. Contact with Alien Civilizations: Our Hopes and Fears about Encountering Extraterrestrials;Michaud,2007
4. S. Dick, Life on Other Worlds: The 20th Century Extraterrestrial Life Debate, Cambridge University Press, 1998.
5. Mars and its Canals;Lowell,1906