Columbia subject headings:
Hoover, Herbert, 1874-1964.
Poland--Foreign relations--1918-1945.
Poland--Foreign relations--United States.
United States--Foreign relations--1929-1933.
United States--Foreign relations--Poland.
Harvard subject headings:
Hoover, Herbert, 1874-1964.
Poland--Foreign relations--1918-1945
Poland--Foreign relations--United States
United States--Foreign relations--1929-1933.
United States--Foreign relations--Poland.
Princeton subject headings: