Columbia subject headings:
Secession.
United States--History--Civil War, 1861-1865--Causes.
United States--Politics and government--1857-1861.
Harvard subject headings:
Secession.
United States--History--Civil War, 1861-1865--Causes.
United States--Politics and government--1857-1861.
Princeton subject headings:
Secession.
Slavery--United States--Controversial literature--1861.
United States--Politics and government--1857-1861.