@misc{indiciae7db0c6f83734,
  title = {A seismic refraction system for lunar use.},
  author = {Kerr, J. and Kovach, R. L. and Mcallister, B. D. and Watkins, J. and Zimmer, J.},
  year = {1969},
  url = {https://ntrs.nasa.gov/citations/19690063544},
  note = {Source identifier: 19690063544}
}