@misc{indiciae8788aebe061a,
  title = {Map showing mineral resources of Montgomery County, Maryland},
  author = {A.J. Froelich},
  year = {1974},
  doi = {10.3133/ofr74153},
  url = {https://pubs.usgs.gov/publication/ofr74153},
  note = {Source identifier: ofr74153}
}