@misc{indiciae2ece0ca7e6c8,
  title = {Research In Helicopter Noise},
  author = {Yu, Yung H. and Schmitz, Frederic H. and Morse, Andrew H.},
  year = {1991},
  url = {https://ntrs.nasa.gov/citations/19910000400},
  note = {Source identifier: 19910000400}
}