@misc{indiciae71c9687f7946,
  title = {Our mineral supplies--Manganiferous iron ores},
  author = {E.C. Harder},
  year = {1919},
  doi = {10.3133/b666ee},
  url = {https://pubs.usgs.gov/publication/b666EE},
  note = {Source identifier: b666EE}
}