Columbia subject headings:
Freed persons--Brazil--History--Congresses.
Middle class--Brazil--History--Congresses.
Slave labor--Brazil--History--Congresses.
Slavery--Brazil--History--Congresses.
Harvard subject headings:
Freed persons--Brazil--History--Congresses.
Middle class--Brazil--History--Congresses.
Slave labor--Brazil--History--Congresses.
Slavery--Brazil--History--Congresses.
Princeton subject headings:
Freed persons--Brazil--History--Congresses.
Middle class--Brazil--History--Congresses.
Slave labor--Brazil--History--Congresses.
Slavery--Brazil--History--Congresses.