Columbia subject headings:
Intelligence service--Confederate States of America--History.
Lincoln, Abraham, 1809-1865--Assassination.
United States--History--Civil War, 1861-1865--Secret service.
Harvard subject headings:
Intelligence service--Confederate States of America--History.
Lincoln, Abraham, 1809-1865--Assassination.
United States--History--Civil War, 1861-1865--Secret service.
Princeton subject headings:
Intelligence service--Confederate States of America--History.
Lincoln, Abraham, 1809-1865--Assassination.
United States--History--Civil War, 1861-1865--Secret service.