@misc{indiciae78255c260ef4,
  title = {National coal resource assessment methodology; comparison of resource calculation methods by two Geographic Information Systems (GIS)},
  author = {S.J. Tewalt},
  year = {1998},
  doi = {10.3133/ofr98365},
  url = {https://pubs.usgs.gov/publication/ofr98365},
  note = {Source identifier: ofr98365}
}