Columbia subject headings:
Black people--Panama--History--20th century.
Labor policy--Panama--Canal Zone--History--20th century.
Labor policy--United States--History--20th century.
Panama--Race relations.
Harvard subject headings:
Black people--Panama--History--20th century.
Labor policy--Panama--Canal Zone--History--20th century.
Labor policy--United States--History--20th century
Panama--Race relations.
Princeton subject headings:
Black people--Panama--History--20th century.
Labor policy--Canal Zone--History--20th century.
Labor policy--United States--History--20th century.
Panama--Race relations.