Columbia subject headings:
Photography--Spain--History--19th century--Congresses.
Photography--Spain--History--20th century--Congresses.
Harvard subject headings:
Photography--Spain--History--19th century--Congresses.
Photography--Spain--History--20th century--Congresses.
Princeton subject headings:
Photography--Spain--History--19th century--Congresses.
Photography--Spain--History--20th century--Congresses.