@misc{indiciae971809548138,
  title = {Shatter cones at Sierra Madera, Texas},
  author = {Keith A. Howard and Terry W. Offield},
  year = {1968},
  doi = {10.1126/science.162.3850.261},
  url = {https://pubs.usgs.gov/publication/70198168},
  note = {Source identifier: 70198168}
}