@misc{indiciaeb1e9c33b53c9,
  title = {Crystal controlled seismic amplifier-calibrator - VCO},
  author = {John C. Lahr},
  year = {1976},
  doi = {10.3133/ofr77116},
  url = {https://pubs.usgs.gov/publication/ofr77116},
  note = {Source identifier: ofr77116}
}