1951c, 1961c, 1970e, 1981c, 1991c, 2001c, 2011c, 2014e. Legend: e-estimate, c-census, o-other, ..
* Unofficial, calculated population.
• Istituto Nazionale di Statistica, Italia National Institute of Statistics (Italy)
• The Sovereign State and Its Competitors: An Analysis of Systems Change. Spruyt, H. (1996), Princeton University Press. ISBN 9780691029108.
• Geodemo Statistiche Demografiche dell'ISTAT
 City density map, generated by population.city using data provided to us by 1km.net website. Every circle is city with population over 5000. Link
Population density map generated by instructions from daysleeperrr on reddig. Link1
Used data source is the Gridded Population of the World (GPW), v3 online at the the Socioeconomic Data and Applications Center (SEDAC) at Columbia University. Link2
Additional urban land cover: Extracted from Global Land Cover Characteristics Data Base Version 2.0 and Binary MOD12Q1 data on shadedrelief.com. Link3