@misc{indiciae538ba3e63b7c,
  title = {Helicity-Density And Normalized-Helicity Maps Of Flows},
  author = {Degani, David and Levy, Yuval and Seginer, Arnan},
  year = {1991},
  url = {https://ntrs.nasa.gov/citations/19910000386},
  note = {Source identifier: 19910000386}
}