@misc{indiciae4fc4d8d5ee47,
  title = {World helicopter market study},
  author = {Cleary, B. and Pearson, R. W. and Greenwood, S. W. and Kaplan, L.},
  year = {1978},
  url = {https://ntrs.nasa.gov/citations/19790025923},
  note = {Source identifier: 19790025923}
}