Columbia subject headings:
Magnetic declination--United States--Maps.
Maps.
United States--Maps.
Harvard subject headings:
Alaska--Maps.
Geomagnetism--Alaska--Maps.
Geomagnetism--Hawaii--Maps.
Geomagnetism--United States--Maps.
Hawaii--Maps.
Magnetic declination--United States--Maps.
United States--Maps.
Princeton subject headings:
Geophysics.
Magnetic declination.
Maps.
United States--Maps.