@misc{indiciaea1b41c5eb0b3,
  title = {Historical survey of U.S. seismograph stations},
  author = {Barbara B. Poppe},
  year = {1979},
  doi = {10.3133/pp1096},
  url = {https://pubs.usgs.gov/publication/pp1096},
  note = {Source identifier: pp1096}
}