@misc{indiciaeffe6f14b7a4b,
  title = {Energy resources of the United States},
  author = {P. K. Theobald and Stanley P. Schweinfurth and Donald Cave Duncan},
  year = {1972},
  doi = {10.3133/cir650},
  url = {https://pubs.usgs.gov/publication/cir650},
  note = {Source identifier: cir650}
}