Columbia subject headings:
Lenses--Design and construction--Congresses.
Lenses--Design and construction--Data processing--Congresses.
Harvard subject headings:
Lenses--Design and construction--Congresses
Lenses--Design and construction--Data processing--Congresses.
Princeton subject headings:
Lenses--Design and construction--Congresses.
Lenses--Design and construction--Data processing--Congresses.