Harder, E.C.Johnston, A. W. (A. Walfred)Map of the principal part of the Cuyuna Iron-ore District, showing the distribution of known iron-bearing rocks and lines of maximum magnetic attraction, scale 1 inch = 1 mile.PDFengMinnesota Geological SurveyPublicPreliminary report on the geology of east central Minnesota, including the Cuyuna iron-ore district, Bulletin 15, Plate 2MapsMinnesota1918University of Minnesota