http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
national industry-occupation employment matrix, 1970, 1978, and projected 1990
U.S. Department of Labor, Bureau of Labor Statistics.
Authors: George T. Silvestri and Joel Segaloff.
Bulletin of the United States Bureau of Labor Statistics ; 2086