TY - RPRT TI - Preliminary report of 1977 coal drilling in eastern Montana and northeastern Wyoming: Geophysical logs for Big Horn County, Montana AU - Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey AU - Montana Bureau of Mines and Geology PY - 1977 DO - 10.3133/ofr77721b UR - https://pubs.usgs.gov/publication/ofr77721B ID - ofr77721B ER -