http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
"Originally prepared to enable researchers to locate correspondence contained in microcopy 234, Letters received by the Office of Indian Affairs, 1824-1880, a microfilm publication of the National Archives and Records Service. The sketches provide brief histories of the field units of the Office of Indian Affairs for that period. Individual sketches are distributed by the Archives in pamphlet form to purchasers of selected rolls of microfilm from among the 962 rolls in the complete collection."
Edition for 1967 published under title: Historical sketches for jurisdictional and subject headings used for the letters received by the Office of Indian Affairs, 1824-80.