@misc{indiciae446a5ea363ac,
  title = {Helium soil gas survey of several collapse features and breccia pipes on the Hualapai Indian Reservation, Arizona},
  author = {G. Michael Reimer and Josh M. Been},
  year = {1987},
  doi = {10.3133/ofr8714},
  url = {https://pubs.usgs.gov/publication/ofr8714},
  note = {Source identifier: ofr8714}
}