Columbia subject headings:
Slavery--United States--Controversial literature.
United States--History--Civil War, 1861-1865--Causes.
United States--Politics and government--1861-1865.
Harvard subject headings:
Slavery--Political aspects--United States--History--19th century
United States--History--Civil War, 1861-1865--Causes.
United States--Politics and government--1861-1865.
Princeton subject headings:
Slavery--United States--Controversial literature.
United States--History--Civil War, 1861-1865--Causes.
United States--Politics and government--1861-1865.