@misc{indiciae21d932fb2812,
  title = {Gas and dust in some recent periodic comets},
  author = {Ahearn, M. F. and Millis, R. L. and Birch, P. V.},
  year = {1979},
  url = {https://ntrs.nasa.gov/citations/19790049778},
  note = {Source identifier: 19790049778}
}