@misc{indiciae72466fdad4a8,
  title = {Coal resource occurrence map of the Heart Rock quadrangle, McKinley County, New Mexico},
  author = {Berge Exploration Inc.},
  year = {1979},
  doi = {10.3133/ofr79642},
  url = {https://pubs.usgs.gov/publication/ofr79642},
  note = {Source identifier: ofr79642}
}