References
Maddren, A.G., 1909, Gold placers of the Innoko district: U.S. Geological Survey Bulletin 379, p. 238-266.Brooks, A.H., 1910, Mineral resources of Alaska, report on progress of investigations in 1909: U.S. Geological Survey Bulletin 442, 426 p.Maddren, A.G., 1911, Gold placer mining developments in the Innoko-Iditarod region: U.S. Geological Survey Bulletin 480, p. 236-270.Brooks, A.H., 1912, The Alaska mining industry in 1911, in Brooks, A.H., and others, Mineral resources of Alaska, 1911: U.S. Geological Survey Bulletin 520, p. 17-44.Eakin, H.M., 1914, The Iditarod-Ruby region, Alaska: U.S. Geological Survey Bulletin 578, 45 p.Brooks, A.H., 1915, Mineral resources of Alaska in 1914: U.S. Geological Survey Bulletin 622, 238 p.Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, 115-245.Williams, J.A., 1950, Mining operations in the Fairbanks district and Innoko and Koyukuk precincts: Alaska Territorial Department of Mines Miscellaneous Report 194-13, 20 p.Cobb, E.H., 1972, Metallic mineral resources map of the Ophir quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-367, 1 sheet, scale 1:250,000.Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction material) in the Iditarod and Ophir quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-576, 101 p.Chapman, R.M., Patton, W.W., and Moll, E.J., 1985, Reconnaissance geologic map of the Ophir quadrangle, Alaska: U.S. Geological Survey Open-File Report 85-203, 1 sheet, 1:250,000 scale.Bundtzen, T.K., Green, C.B., Deagen, J., and Daniels, C.L., 1987, Alaska's mineral industry, 1986: Alaska Division of Geological and Geophysical Surveys, Special Report 40, 68 p.Maddren, A.G., 1910, The Innoko gold-placer district, Alaska, with accounts of the central Kuskokwim valley and the Ruby Creek and Gold Hill placers: U.S. Geological Survey Bulletin 410, 87 p.Saunders, R.H., 1960, Itinerary report on a trip to the Flat and Ophir Districts: Alaska Territorial Department of Mines Itinerary Report 64-2, 15 p.