Norsk definisjon av sentralitet  fra Statistisk Sentralbyrå: http://www4.ssb.no/stabas/ClassificationFrames.asp?ID=919597&Language=nn

New conceptualisation of settlement for demography: Beyond the rurban/urban dichotomy
Graeme Hugo, Anthony Champion and Alfredo Lattes. Paper Prepared for Session 42, IUSSP Conference, Bahia, Brazil, June 2001

Geographical classifications to guide rural health policy in Australia
Matthew R McGrail and John S Humphreys. Australia and New Zealand Health Policy 2009