Columbia subject headings:
Niépce, Nicéphore, 1765-1833--Congresses.
Photography--History--Congresses.
Harvard subject headings:
Photography, Artistic--History--Congresses.
Photography--History--Congresses.
Princeton subject headings:
Niépce, Nicéphore, 1765-1883.
Photography, Artistic--History--Congresses.
Photography--History--Congresses.