Columbia subject headings:
Communism--Spain--History--Bibliography.
Communists--Bibliography.
Dialectical materialism--Bibliography.
Socialism--Spain--History--Bibliography.
Harvard subject headings:
Communism--Spain--History--Bibliography.
Princeton subject headings:
Communism--Spain--History--Bibliography.
Communists--Bibliography.
Dialectical materialism--Bibliography.
Socialism--Spain--History--Bibliography.