@misc{indiciae5a0ce3f4c339,
  title = {Milder Etchant For Penetrant Inspection},
  author = {O'Tousa, Joseph E. and Thomas, Clark S.},
  year = {1990},
  url = {https://ntrs.nasa.gov/citations/19900000462},
  note = {Source identifier: 19900000462}
}