@book{149164,
	author = {National Geomagnetic Information Center U.S.},
	title = {USGS/NGIC geomagnetic observatory data},
	publisher = {U.S. Geological Survey, National Geomagnetic Information Center},
	year = {1991-},
	address = {Denver, Colo.},
	note = {Title from disk label.}
}