@misc{indiciae0494e9782d32,
  title = {Sketches of a hammer-impact, spiked-base, shear-wave source},
  author = {W.P. Hasbrouck},
  year = {1983},
  doi = {10.3133/ofr83917},
  url = {https://pubs.usgs.gov/publication/ofr83917},
  note = {Source identifier: ofr83917}
}