References
[Luce et al., 1990]
Luce, R. Duncan; Krantz, David H.; Suppes, Patrick, and Tversky, Amos. Foundations of measurement: representation, axiomatization, and invariance. San Diego; London: Academic Press; 1990. ISBN: 0-12-425403-9.
Cyberspace geography visualization - 15 October 1995
Luc Girardin, The Graduate Institute of International Studies