@misc{indiciaee7e908eaceb5,
  title = {Helium and radon soil-gas surveys of collapse features on the Hualapai Indian Reservation},
  author = {J.M. Been and S.L. Szarzi},
  year = {1989},
  doi = {10.3133/ofr89486},
  url = {https://pubs.usgs.gov/publication/ofr89486},
  note = {Source identifier: ofr89486}
}