@misc{indiciaea6617d597776,
  title = {Detection of tunnels by transient electromagnetic subsurface imaging},
  author = {B.A. James},
  year = {1988},
  doi = {10.3133/ofr88218},
  url = {https://pubs.usgs.gov/publication/ofr88218},
  note = {Source identifier: ofr88218}
}