NASA Exobiology Division
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Web Resources
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Book References
Discussed by Billingham, John and Pierson, Thomas in “SETI 2020 : A Roadmap for the Search for Extraterrestrial Intelligence” (2002) (edited by Elkers, Ronald D and Cullers, Kent D and Billingham, John and Scheffer, Louis K) (available on Amazon USA and on Amazon UK) at page xxxiv (in the Preface) of the SETI Press softcover edition.
Other Material