http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Classification bulletin of U.S. Patent Office from Jan. 1, 1927 to June 30, 1927, containing classification of subjects of invention revised by Classification Division of U.S. Patent Office
Electronic reproduction. [Bethesda, Md.] : ProQuest, 2014. digital, PDF file. ProQuest U.S. Executive Branch Documents Mode of access: World Wide Web via ProQuest website.