1. E.R. Berlekamp, J.H. Conway, R.K. Guy, Winning Ways for your Mathematical Plays, vol. 2, Academic Press, New York, 1982, xxxi+850pp.; see also second ed., vol. 3, A K Peters, 2003, p. 643.
2. J.H. Conway, The Angel problem, in: R.J. Nowakowski (Ed.), Games of No Chance, Cambridge, 1996, pp. 3–12.
3. M. Kutz, Conway's Angel in three dimensions, manuscript.