@misc{indiciaec30c23e25a27,
  title = {A code generating self-calibrating seismic amplifier, with a section on crystal VCO center frequency stabilizer},
  author = {John R. Van Schaack and E. Gray Jensen},
  year = {1980},
  doi = {10.3133/ofr80387},
  url = {https://pubs.usgs.gov/publication/ofr80387},
  note = {Source identifier: ofr80387}
}