@misc{indiciae6934cb9a858b,
  title = {Mercury concentration in coal — Unraveling the puzzle},
  author = {B. Toole-O’Neil and S.J. Tewalt and R. B. Finkelman and D.J. Akers},
  year = {1999},
  doi = {10.1016/s0016-2361(98)00112-4},
  url = {https://pubs.usgs.gov/publication/70020900},
  note = {Source identifier: 70020900}
}