@misc{indiciaee280f3294711,
  title = {Noise reduction techniques for propellers and engines},
  author = {Crigler, J. L. and Hubbard, H. H. and Maglieri, D. J.},
  year = {1969},
  url = {https://ntrs.nasa.gov/citations/19690012374},
  note = {Source identifier: 19690012374}
}