@misc{indiciaefed02754a330,
  title = {Geochemistry of minor elements in coals of the Northern Great Plains coal province},
  author = {Peter Zubovic and Taisia Maximovna Stadnichenko and Nola B. Sheffey},
  year = {1961},
  doi = {10.3133/b1117a},
  url = {https://pubs.usgs.gov/publication/b1117A},
  note = {Source identifier: b1117A}
}