@misc{indiciaeff2b4c7834a1,
  title = {The area of influence of an exploratory hole},
  author = {D.A. Singer and L. J. Drew},
  year = {1976},
  doi = {10.2113/gsecongeo.71.3.642},
  url = {https://pubs.usgs.gov/publication/70197188},
  note = {Source identifier: 70197188}
}