@misc{indiciae5d2665d16e99,
  title = {Chemical composition of sedimentary rocks in Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, and Wyoming},
  author = {Thelma P. Hill and Marian A. Werner and M. Julia Horton},
  year = {1967},
  doi = {10.3133/pp561},
  url = {https://pubs.usgs.gov/publication/pp561},
  note = {Source identifier: pp561}
}