Columbia subject headings:
Center for Research Libraries (U.S.)--Microform catalogs.
Documents on microfilm--Catalogs.
United States--History--Sources--Bibliography--Microform catalogs.
United States. National Archives and Records Administration--Indexes.
Harvard subject headings:
Center for Research Libraries (U.S.)--Microform catalogs.
Documents on microfilm--Catalogs.
United States--History--Bibliography--Microform catalogs.
United States--History--Sources--Bibliography--Microform catalogs.
United States. National Archives and Records Administration--Indexes.
Princeton subject headings:
Catalogs.
Center for Research Libraries (U.S.)--Microform catalogs.
Documents on microfilm--Catalogs.
United States--History--Sources--Bibliography--Microform catalogs.
United States. National Archives and Records Administration--Indexes.