@misc{indiciae266a1131e30b,
  title = {Microcrack closure in rocks under stress - Direct observation},
  author = {Batzle, M. L. and Simmons, G. and Siegfried, R. W.},
  year = {1980},
  url = {https://ntrs.nasa.gov/citations/19810033737},
  note = {Source identifier: 19810033737}
}