@misc{indiciaeecd167e3869b,
  title = {Geomagnetic activity and Hale sector boundaries},
  author = {Lundstedt, H. and Scherrer, P. H. and Wilcox, J. M.},
  year = {1981},
  url = {https://ntrs.nasa.gov/citations/19810040984},
  note = {Source identifier: 19810040984}
}