Columbia subject headings:
Harvard subject headings:
Partido Obrero de Unificación Marxista.
Spain--History--Civil War, 1936-1939.
Spain--Politics and government--1931-1939.
Princeton subject headings:
Partido Obrero de Unificación Marxista.
Spain--History--Civil War, 1936-1939.
Spain--Politics and government--1931-1939.