@misc{indiciae6b0650f0272f,
  title = {Organic-rich shale of the United States and world land areas},
  author = {Donald Cave Duncan and Vernon Emanuel Swanson},
  year = {1965},
  doi = {10.3133/cir523},
  url = {https://pubs.usgs.gov/publication/cir523},
  note = {Source identifier: cir523}
}