@misc{indiciae20b4f4534b94,
  title = {Trace element geochemistry of altered volcanic ash layers (tonsteins) in late Permian coal-bearing formations of eastern Yunnan and western Guizhou Provinces, China},
  author = {Y. Zhou and B.F. Bohor and Y. Ren},
  year = {2000},
  doi = {10.1016/s0166-5162(00)00017-3},
  url = {https://pubs.usgs.gov/publication/70022514},
  note = {Source identifier: 70022514}
}