@misc{indiciae405d1d466822,
  title = {Geophysical investigations in deep horizontal holes drilled ahead of tunnelling},
  author = {R. D. Carroll and M.J. Cunningham},
  year = {1980},
  doi = {10.1016/0148-9062(80)90261-2},
  url = {https://pubs.usgs.gov/publication/70012277},
  note = {Source identifier: 70012277}
}