@misc{indiciaef9c2dc8426b6,
  title = {Manganese contents of some sedimentary rocks of Paleozoic age in Virginia},
  author = {Eric R. Force and Leslie J. Cox},
  year = {1991},
  doi = {10.3133/b1916},
  url = {https://pubs.usgs.gov/publication/b1916},
  note = {Source identifier: b1916}
}