@misc{indiciaed2eaab3a8dfc,
  title = {Analysis of geomagnetic secular variation during 1980-1985 and 1985- 1990, and geomagnetic models proposed for the 1991 revision of the International Geomagnetic Reference Field},
  author = {N.W. Peddie},
  year = {1992},
  doi = {10.5636/jgg.44.735},
  url = {https://pubs.usgs.gov/publication/70016829},
  note = {Source identifier: 70016829}
}