After hearing Ken Hollings read an excerpt from Welcome To Mars at the Atom Town screening last week, I borrowed a copy at the weekend and began reading it. I'm only 47 pages in so far, but it's already amazing. One of the things referenced in it was John Von Neumann's 1948 paper ‘The General and Logical Theory Of Automata' which “enlarges upon Turing's idea of a Universal Machine by proposing a tape-driven, self-producing ‘automaton whose output is other automata'” -
A swift google search turns up a pdf of the published paper here