Columbia subject headings:
Niger--Social conditions.
Slavery--Niger--History.
Slavery--Niger.
Harvard subject headings:
Antislavery movements--Niger.
Human rights--Niger.
Slavery--Law and legislation--Niger.
Slavery--Niger--History.
Slaves--Niger--Social conditions.
Princeton subject headings:
Antislavery movements--Niger.
Human rights--Niger.
Slavery--Law and legislation--Niger.
Slavery--Niger--History.