http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Abundance and distribution of thorium in the carbonatite stock at Iron Hill, Powderhorn District, Gunnison County, Colorado
by Theodore J. Armbrustmacher ; prepared in cooperation with the Department of Energy.
Geological Survey professional paper ; 1049-B
Geology and resources of thorium in the United States