@book{ Solr-arto.000642205, title = {Polna-joen ongelma}, series = {Eripainossarja / Oulun yliopisto. Historian laitos}, author = {Julku, Kyösti, 1931-2007}, address = {Oulu}, publisher = {Oulun yliopisto}, year = {1989}, note = {Erip.: Faravid 1988, 12.}, }