1. Angelidis, M. (2003). Analysis of polycentric developments. A Research Note: ESPON 1.1.3. Athens: National Technical University of Athens.
2. Atlas Ost- und Südosteuropa (1997). Zentrensysteme in Mittel- und Osteuropa. 5.3. Wien: Österreichisches Ost- und Südosteuropa Institut.
3. Bourne, L. S. (1995). Urban systems in an era of global restructuring: expanding the research agenda. In M. Palomäki, & J. A. Karunaratne (Eds.), Urban development and urban life (pp. 15–39). Vaasa: Universitas Wasaensis.
4. Bourne, L. S. (1997). Polarities of structure and change in urban systems: A Canadian example. GeoJournal, 43, 339–349.
5. Demarie M. (Ed.). (1995). Città capitali dell’ Europe centrale: politiche e strategie urbane nel nuovo spazio europea. Contributi di ricerca. Torino: Fondazione Giovanni Agnelli.