@misc{indiciae158bb3416b9b,
  title = {Geophysical Investigations 4 and 4a},
  author = {W.J. Dempsey and M. E. Hill and J. R. Henderson},
  year = {1947},
  doi = {10.3133/ofr4723},
  url = {https://pubs.usgs.gov/publication/ofr4723},
  note = {Source identifier: ofr4723}
}