@misc{indiciae177baac1fc2b,
  title = {An active noise reduction system for aircrew helmets},
  author = {Wheeler, P. D. and Rawlinson, D. and Pelc, S. F. and Dorey, T. P.},
  year = {1978},
  url = {https://ntrs.nasa.gov/citations/19790002682},
  note = {Source identifier: 19790002682}
}