Reference | JOHNSON, A.M. AND GROTH, E.H., 1998, INVENTORY OF UNDERGROUND MINES, ONTONAGON COUNTY, P. 37-38, SITE ID # 660017, MICHIGAN DEPARTMENT OF JOHNSON, A.M. AND GROTH, E.H., 1998, INVENTORY OF UNDERGROUND MINES, ONTONAGON COUNTY, P. 37-38, SITE ID # 660017, MICHIGAN DEPARTMENT OF NATURAL RESOURCES. |