http://digfir-published.macmillanusa.com/astro_tutorial/astro_tutorial_ch28_the_search_for_extraterrestrial_life.html
Chapter
28. The Search for Extraterrestrial Life
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http://digfir-published.macmillanusa.com/astro_tutorial/astro_tutorial_ch28_the_search_for_extraterrestrial_life_dlap.xmlDLAP questions51a577b6b11c0fe63c000000