@misc{indiciaea2a24a2ad975,
  title = {Texas Instruments Model 59 hand-calculator program for interpretation of refraction seismic data over up to four dipping layers},
  author = {David L. Campbell},
  year = {1979},
  doi = {10.3133/ofr791662},
  url = {https://pubs.usgs.gov/publication/ofr791662},
  note = {Source identifier: ofr791662}
}