@misc{indiciaecb0f0e899e3a,
  title = {Contributions to economic geology, 1909, part II, mineral fuels--Coal and lignite},
  author = {Charles Butts and M.R. Campbell and E. G. Woodruff and Charles T. Lupton and J. S. Diller and M. A. Pishel and H. E. Gregory and A. C. Veatch},
  year = {1911},
  doi = {10.3133/b431b},
  url = {https://pubs.usgs.gov/publication/b431B},
  note = {Source identifier: b431B}
}