Columbia subject headings:
Harvard subject headings:
Slave labor--America--History--19th century.
Slave labor--Atlantic Ocean Region--History--19th century.
Slave trade--America--History--19th century.
Slave trade--Atlantic Ocean Region--History--19th century.
Slavery--America--History--19th century.
Slavery--Atlantic Ocean Region--History--19th century.
Princeton subject headings:
Slave labor--America--History--19th century.
Slave labor--Atlantic Ocean Region--History--19th century.
Slave labor--History--19th century.
Slavery--America--History--19th century.
Slavery--History--19th century.