@article{684,
  author = {J. Thomas and N. Weiss and S. Tobias and N. Brummell},
  title = {Downward pumping of magnetic flux as the cause of filamentary structures in sunspot penumbrae},
  year = {2002},
  journal = {Nature},
  volume = {420},
  pages = {390-393},
  month = {Apr-11-2004},
  issn = {0028-0836},
  url = {http://www.nature.com/doifinder/10.1038/nature01174},
  doi = {10.1038/nature01174},
}