@misc{indiciae0847b50908e7,
  title = {The magnetospheric disturbance ring current as a source for probing the deep earth electrical conductivity},
  author = {W.H. Campbell},
  year = {1990},
  doi = {10.1007/bf00878018},
  url = {https://pubs.usgs.gov/publication/70015731},
  note = {Source identifier: 70015731}
}