@article{8410,
  author = {S. Kawaler and D. Winget and I. Iben and Carl Hansen},
  title = {Evolutionary period changes in variable helium-rich white dwarfs},
  year = {1986},
  journal = {The Astrophysical Journal},
  volume = {302},
  pages = {530},
  month = {Jan-03-1986},
  issn = {0004-637X},
  url = {http://articles.adsabs.harvard.edu/full/1986ApJ...302..530K},
  doi = {10.1086/164013},
}