@conference{7331,
  author = {W. Hagen and D. Dickinson and R. Humphreys and R. Stencel},
  title = {A Comparison of Circumstellar Gas and Dust in M Giants and Supergiants},
  year = {1982},
  url = {http://articles.adsabs.harvard.edu/full/1982SAOSR.392A.231H},
  note = {JILA Pub. 2406},
}