@misc{indiciaea8c55bd09a02,
  title = {Chemical analysis of 45 Maryland coal samples},
  author = {Charles L. Oman and Linda J. Bragg and H.M. Nock and L.J. Schwarz and J.L. Harris and N. H. Rega and S.S. Crowley},
  year = {1981},
  doi = {10.3133/ofr811099},
  url = {https://pubs.usgs.gov/publication/ofr811099},
  note = {Source identifier: ofr811099}
}