@misc{indiciae4d7410ae0d5f,
  title = {A summary of the U.S. Geological Survey 1999 resource assessment of selected coal zones in the Northern Rocky Mountains and Great Plains region, Wyoming, Montana, and North Dakota},
  author = {M.S. Ellis and D. J. Nichols},
  year = {2002},
  doi = {10.3133/b2189},
  url = {https://pubs.usgs.gov/publication/b2189},
  note = {Source identifier: b2189}
}