@misc{indiciae8ebf6564e662,
  title = {IGRFGRID : a program for creation of a total magnetic field (International Geomagnetic Reference Field) grid representing the earth's main magnetic field, Part B - Source code},
  author = {Ronald E. Sweeney},
  year = {1990},
  doi = {10.3133/ofr9045b},
  url = {https://pubs.usgs.gov/publication/ofr9045B},
  note = {Source identifier: ofr9045B}
}