Columbia subject headings:
Belgium--Foreign relations--France.
France--Foreign relations--Belgium.
World War, 1939-1945--Belgium.
World War, 1939-1945--France.
Harvard subject headings:
Belgium--Foreign relations--France.
France--Foreign relations--Belgium.
Neutrality--Belgium.
World War, 1939-1945--Belgium.
World War, 1939-1945--Campaigns--France.
World War, 1939-1945--France.
Princeton subject headings:
Belgium--Foreign relations--France.
France--Foreign relations--Belgium.
World War, 1939-1945--Belgium.
World War, 1939-1945--France.