http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Independent Petroleum Association of America
Monthly (except May/June and Nov./Dec.), Jan. 1990-Nov./Dec. 1992
Monthly (except Jan./Feb., May/June, and Nov./Dec. 1993
Oil & natural gas producing industry in your state