PRELIMINARY RECONNAISSANCE GEOLOGIC MAP OF THE PETERSBURG AND PARTS OF THE PORT ALEXANDER AND SUMDUM 1:250,000 QUADRANGLES, SOUTHEASTERN ALASKA
Brew, D. A., Ovenshine, A. T., Karl, S. M., and Hunt, S. J., 1984, Preliminary reconnaissance geologic map of the Petersburg and parts of the Port Alexander and Sumdum 1:250,000 quadrangles, southeastern Alaska: U.S. Geological Survey Open-File Report 84-0405, 42 p., 1 plate, scale 1:250,000.