Columbia subject headings:
Blockade.
Contraband of war.
Search, Right of.
World War, 1914-1918--Blockades.
Harvard subject headings:
Blockade.
Contraband of war.
Search, Right of.
World War, 1914-1918--Blockades
Princeton subject headings:
Blockade.
Contraband of war.
Search, Right of.
World War, 1914-1918--Blockades.