Columbia subject headings:
Canada--History--Abstracts--Periodicals.
Canada--History--Indexes--Periodicals.
United States--History--Abstracts--Periodicals.
United States--History--Periodicals.
Harvard subject headings:
Canada--History--Abstracts--Periodicals.
Canada--History--Indexes--Periodicals.
United States--History--Abstracts--Periodicals.
United States--History--Periodicals.
Princeton subject headings:
Canada--History--Periodicals--Indexes--Periodicals.
United States--History--Periodicals--Indexes--Periodicals.