@misc{indiciae514ef512fdca,
  title = {Analytical methods in geochemical investigations of the Pierre Shale},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1972},
  doi = {10.3133/pp391},
  url = {https://pubs.usgs.gov/publication/pp391},
  note = {Source identifier: pp391}
}