1. Alexander, C., 1966, A City is not a Tree, Architectural Forum. 122(1): 58–61, and 122(2): 58–62.
2. Barabási, A-L., 2002, Linked: The New Science of Networks, Perseus Pub, New-York.
3. Barabási, A-L., and Albert, R., 1999, Emergence of Scaling in Random Networks, Science. 286: 509–512.
4. Batty, M. and Shiode, N., 2003, Population Growth Dynamics in Cities, Countries and Communication Systems, in: Advanced Spatial Analysis, P. A. Longley and M. Batty, eds., ESRI Press, Redlands, CA, pp. 327–343.
5. Beckmann, M. J., 1958, City Hierarchies and the Distribution of City Size, Economic Development and Cultural Change. 6: 243–248.