@misc{indiciae4d1899702b4c,
  title = {Classes of ring galaxies generated by dynamical friction},
  author = {Luban-Lotan, Pnina and Struck-Marcell, Curtis},
  year = {1989},
  url = {https://ntrs.nasa.gov/citations/19890065687},
  note = {Source identifier: 19890065687}
}