http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Reports and maps of the Geological Survey released only in the open files, 1962
by Betsy A. Weld, Erwin A. Asselstine, and Arthur Johnson.
From May 1975, open-file reports are announced in the monthly list, New publications of the Geological Survey (ref Z 6034 U49 U53) and listed in the annual catalogs of the Survey's publications.