@misc{indiciae9f3b357264d4,
  title = {Self-calibrating seismic amplifier and telemetry system},
  author = {John R. Van Schaack},
  year = {1975},
  doi = {10.3133/ofr7564},
  url = {https://pubs.usgs.gov/publication/ofr7564},
  note = {Source identifier: ofr7564}
}