@misc{indiciae78654c0aebee,
  title = {Working drawings of a Kirk shear wave source},
  author = {Wilfred P. Hasbrouck},
  year = {1977},
  doi = {10.3133/ofr77622},
  url = {https://pubs.usgs.gov/publication/ofr77622},
  note = {Source identifier: ofr77622}
}