An excellent guide to the theory of NP-completeness is [Garey et al., 1979]. Combinatorial reasoning is analysed in [Tucker, 1995]. Other documents related to computational complexity are [Bonuccelli et al., 1994][Brauer et al., 1984][Miller and Orlin, 1985].
Cyberspace geography visualization - 15 October 1995
Luc Girardin, The Graduate Institute of International Studies