Columbia subject headings:
Ríos, Fernando de los, 1879-1949--Congresses.
Socialism--Spain--Andalusia--History--Congresses.
Harvard subject headings:
Ríos, Fernando de los, 1879-1949--Congresses.
Socialism--Spain--Andalusia--History--Congresses.
Princeton subject headings:
Ríos, Fernando de los, 1879-1949--Congresses.
Socialism--Spain--Andalusia--History--Congresses.