@misc{indiciae9e7cd29cba9a,
  title = {Impact cratering calculations},
  author = {Ahrens, Thomas J. and Okeefe, J. D. and Smither, C. and Takata, T.},
  year = {1991},
  url = {https://ntrs.nasa.gov/citations/19920001715},
  note = {Source identifier: 19920001715}
}