Columbia subject headings:
Petroleum workers--Colombia--Barrancabermeja.
Working class--Colombia--Barrancabermeja.
Harvard subject headings:
Petroleum workers--Colombia--Barrancabermeja.
Working class--Colombia--Barrancabermeja.
Princeton subject headings:
Barrancabermeja (Colombia)--History.
Mahecha Caycedo, Raúl Eduardo, 1884-1940.
Socialists--Colombia--Biography.
Working class--Colombia--Barrancabermeja.