@misc{indiciaefcdf33c6c578,
  title = {Analyses of Illinois coal and associated rock samples collected in 1975 and 1976},
  author = {Charles L. Oman},
  year = {1994},
  doi = {10.3133/ofr94555},
  url = {https://pubs.usgs.gov/publication/ofr94555},
  note = {Source identifier: ofr94555}
}