Retrieved 2015-07-05. ↑ Committee on the Limits of Organic Life in Planetary Systems, Committee on the Origins and Evolution of Life, National Research Council; ; The National Academies Press, 2007; page 74 ↑ Jonathan Lunine "Saturn’s Titan: A Strict Test for Life’s Cosmic Ubiquity" (accepted for publication in Proceedings of the American Philosophical Society), July 21, 2009 (Revised November 7, 2009) 1 2 Sagan, Carl (1979). Broca's Brain - the Romance of Science. Hodder and Stoughton.