Lahti, S., J. Rusanen, S. Kärkkäinen, S. Kortelainen, and H. Hausen. “GIS and Areal Variation in Dental Caries – Contribution of Socio-Economic Factors Among 6-Year-Olds in Kemi, Finland”. Nordia Geographical Publications, vol. 33, no. 2, Jan. 2004, pp. 1–8, https://nordia.journal.fi/article/view/76226.