@misc{indiciae4b72ad2d3cc6,
  title = {Industrial minerals, today and tomorrow; the raw materials to build the upper Midwest},
  author = {P. K. Sims and Sarah Chadima and R.F. Biek},
  year = {1992},
  doi = {10.3133/ofr92514},
  url = {https://pubs.usgs.gov/publication/ofr92514},
  note = {Source identifier: ofr92514}
}