Columbia subject headings:
Harvard subject headings:
Ambassadors--Canada--Biography.
Canada--Foreign relations--1945-
Canada--Foreign relations--United States.
Ritchie, Charles, 1906-
Ritchie, Charles, 1906-1995.
United States--Foreign relations--Canada.
Princeton subject headings:
Ambassadors--Canada--Biography.
Canada--Foreign relations--1945-
Canada--Foreign relations--United States.
Ritchie, Charles, 1906-1995.
United States--Foreign relations--Canada.