https://www.ngdc.noaa.gov/geomag/faqgeom.shtml#Is_Earths_magnetic_field_going_to_reverse
https://maps.ngdc.noaa.gov/viewers/historical_declination/
https://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html
Magnetometer pdf local copy
GeoMagnetism (last edited 2019-03-08 21:23:21 by KeithLofstrom)