Columbia subject headings:
Belgium--History--German occupation, 1914-1918.
Neutrality--Belgium.
World War, 1914-1918--Belgium.
Harvard subject headings:
Belgium--History--German occupation, 1914-1918.
Neutrality--Belgium.
World War, 1914-1918--Belgium
Princeton subject headings:
Belgium--History--German occupation, 1914-1918.
Neutrality--Belgium.
World War, 1914-1918--Belgium.