@misc{indiciae33c38393dd12,
  title = {Chemical analyses for selected minor elements in Pierre shale},
  author = {Lloyd Forrest Rader and F. S. Grimaldi},
  year = {1961},
  doi = {10.3133/pp391a},
  url = {https://pubs.usgs.gov/publication/pp391A},
  note = {Source identifier: pp391A}
}