1. V Batagelj, and A Mrvar, 1997, Networks/Pajek: Program for Large Networks Analysis . WWW document, http://vlado.fmf.uni-lj.si/pub/networks/pajek/
2. Centrality in social networks conceptual clarification
3. P Hojholt, 1995, Generalization of Built-up Areas Using Kohonen-networks . In Proceedings of Eurocarto XIII, 2 -4 October, Ispra, Italy