Columbia subject headings:
Preservation of materials--Congresses.
United States--Statistical services--Congresses.
United States. National Archives and Records Service--Congresses.
Harvard subject headings:
Preservation of materials--Congresses.
United States--Statistical services--Congresses.
United States. National Archives and Records Service--Congresses.
Princeton subject headings:
Preservation of materials--Congresses.
United States--Statistical services--Congresses.
United States. National Archives and Records Service--Congresses.