@misc{indiciaed390bcec0259,
  title = {A device for introducing helical perturbations into a trailing line vortex},
  author = {Ash, Robert L. and Riester, John E., Jr.},
  year = {1990},
  url = {https://ntrs.nasa.gov/citations/19900051701},
  note = {Source identifier: 19900051701}
}