"David H. Levy - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 14 May 2012. http://en.wikipedia.org/wiki/David_H._Levy.
"About David." Welcome. N.p., n.d. Web. 14 May 2012. http://www.jarnac.org/aboutdavid.htm.
"David H. Levy (Canadian astronomer and science writer) -- Britannica Online Encyclopedia." Britannica Online Encyclopedia. N.p., n.d. Web. 14 May 2012. http://www.britannica.com/EBchecked/topic/338050/David-H-Levy.
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