@misc{indiciae1bb09f2409ff,
  title = {Tip-path-plane angle effects on rotor blade-vortex interaction noise levels and directivity},
  author = {Burley, Casey L. and Martin, Ruth M.},
  year = {1988},
  url = {https://ntrs.nasa.gov/citations/19890031543},
  note = {Source identifier: 19890031543}
}