Columbia subject headings:
Books on microfilm--Standards--Congresses.
Library materials--Reproduction--Congresses.
Microfilms--Congresses.
Micrographics--Congresses.
Harvard subject headings:
Books on microfilm--Standards--Congresses.
Library materials--Reproduction--Congresses.
Microfilms--Congresses.
Micrographics--Congresses.
Princeton subject headings:
Books on microfilm--Standards--Congresses.
Library materials--Reproduction--Congresses.
Microfilms--Congresses.
Micrographics--Congresses.