@misc{indiciae73bc7f1ed8f3,
  title = {Metal content of crude petroleums},
  author = {J.S. Ball and W.J. Wenger and H.J. Hyden and C. A. Horr and A.T. Myers},
  year = {1956},
  url = {https://pubs.usgs.gov/publication/70010473},
  note = {Source identifier: 70010473}
}