GB Patent 630,726, Improvements in or relating to the transmutation of chemical elements, Leo Szilard, 1936 (filed 1934)
US Patent 2,708,656, Neutronic Reactor, Enrico Fermi and Leo Szilard, 1955 (filed 1944)
video on demand
Retrobites: Atomic Bomb: Szilard (1960), Canadian Broadcasting Corporation. Physicist Leo Szilard explains how he came up with the idea for the atomic bomb.
Knowledge or Certainty (6/7), The Ascent of Man, BBC, 1973. Jacob Bronowski tells the story of his friend Leo Szilard's work on the atomic bomb from its conception to its use in warfare.
The Vela Incident, Paul Drye, Passing Strangeness (7 February 2009).
The Vela Incident, Alan Bellows, Damn Interesting (16 October 2007).
The Vela Incident: Nuclear Test or Meteoroid? National Security Archive Electronic Briefing Book No. 190 (5 May 2006). This web page comes with a great list of original, declassified source material.
Proliferation: A flash from the past, David Albright and Corey Gay, Bulletin of the Atomic Scientists, vol. 53, no. 06 (November/December 1997): 15-17.