@misc{indiciaef304ed2659fa,
  title = {Origin and distribution of tonsteins in late permian coal seams of Southwestern China},
  author = {Yinzhu Zhou and Y.-L. Ren and B.F. Bohor},
  year = {1982},
  doi = {10.1016/0166-5162(82)90015-5},
  url = {https://pubs.usgs.gov/publication/70011872},
  note = {Source identifier: 70011872}
}