@misc{indiciae405e936d3fe8,
  title = {A geostatistical approach to predicting sulfur content in the Pittsburgh coal bed},
  author = {W.D. Watson and L.F. Ruppert and L. J. Bragg and S.J. Tewalt},
  year = {2001},
  doi = {10.1016/s0166-5162(01)00035-0},
  url = {https://pubs.usgs.gov/publication/70023453},
  note = {Source identifier: 70023453}
}