Columbia subject headings:
United States--Politics and government--19th century--Abstracts.
United States--Politics and government--20th century--Abstracts.
Harvard subject headings:
United States--Politics and government--19th century--Abstracts.
United States--Politics and government--20th century--Abstracts.
Princeton subject headings:
United States--Politics and government--19th century--Abstracts.
United States--Politics and government--20th century--Abstracts.