http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Possibilities of oil and gas in north-central Montana
1 online resource (pages 49-91, 4 unnumbered pages of plates) : illustrations.
Bulletin (Geological Survey (U.S.)) ; no. 641-C
Contributions to economic geology ; 1916, pt. II