@misc{indiciaed81ffb9cda82,
  title = {The occurrence of minor elements in ash of low-rank coal from Texas, Colorado, North Dakota, and South Dakota},
  author = {Maurice Deul and C. S. Annell},
  year = {1956},
  doi = {10.3133/b1036h},
  url = {https://pubs.usgs.gov/publication/b1036H},
  note = {Source identifier: b1036H}
}