@misc{indiciaeef91f3849104,
  title = {Wake Geometry Effects on Rotor Blade-Vortex Interaction Noise Directivity},
  author = {Martin, R. M. and Marcolini, Michael A. and Splettstoesser, W. R. and Schultz, K.-J.},
  year = {1990},
  url = {https://ntrs.nasa.gov/citations/19910003002},
  note = {Source identifier: 19910003002}
}