Muilu, Toivo, Jarmo Rusanen, and Arvo Naukkarinen. 2001. “Supporters and Dependants: The Concept of Economic Dependency Ratio As an Indicator of Changes in Regional Structures in Finland in 1989-1997”. Fennia - International Journal of Geography 179 (1):71-87. https://fennia.journal.fi/article/view/9184.