@misc{indiciaea28ed08046ad,
  title = {Effects of layered sediments on the guided wave in crosswell radar data},
  author = {K.J. Ellefsen},
  year = {1999},
  doi = {10.1190/1.1444674},
  url = {https://pubs.usgs.gov/publication/70021165},
  note = {Source identifier: 70021165}
}