Hong and Page, “Groups”, p. 16389.

Jerome M. O’Connor, “Churchill’s ULTRA Secret of the Century”, September 2000, http://www.historyarticles.com/bletchley_park.htm

Steve Lohr, “Netfix Awards $1 Million Prize and Starts a New Contest”, Bits (blog), New York Times, September 21, 2009, http://bits.blogs.nytimes.com/2009/09/21/netfix-awards-1-million-prize-and-starts-a-new-contest/; “Academy Interview: Five Questions for Dr. Scott Page”, NASA, June 30, 2010, http://www.nasa.gov/offces/oce/appel/ask-academy/issues/volume3/AA_3–6_F_interview.html