@article{10441,
  author = {W. Sieber and Ludwig Oster},
  title = {Further evidence for multiple-ring structure in the hollow-cone emission of radio pulsars},
  year = {1977},
  journal = {Astronomy and Astrophysics},
  volume = {61},
  pages = {445, 446},
  url = {http://articles.adsabs.harvard.edu/full/1977A\%26A....61..445S},
  note = {JILA Pub. 1606},
}