Columbia subject headings:
Centrale d'education ouvrier (Brussels, Belgium)--History.
Parti socialiste belge.
Working class--Education--Belgium.
Harvard subject headings:
Centrale d'education ouvrier (Brussels, Belgium)--History.
Parti socialiste belge.
Socialism and education--Belgium--History--20th century.
Working class--Education--Belgium--History--20th century.
Princeton subject headings: