@misc{indiciae2c34930e3745,
  title = {Time-distance helioseismology},
  author = {Duvall, T. L., Jr. and Jefferies, S. M. and Harvey, J. W. and Pomerantz, M. A.},
  year = {1993},
  url = {https://ntrs.nasa.gov/citations/19930050965},
  note = {Source identifier: 19930050965}
}