@misc{indiciae9cf00d75ac27,
  title = {A cloud/particle model of the interstellar medium - Galactic spiral structure},
  author = {Levinson, F. H. and Roberts, W. W., Jr.},
  year = {1981},
  url = {https://ntrs.nasa.gov/citations/19810050781},
  note = {Source identifier: 19810050781}
}