Columbia subject headings:
Baltic Sea--History.
World War, 1939-1945--Refugees.
World War, 1939-1945--Search and rescue operations--Baltic Sea.
Harvard subject headings:
Baltic Sea--History.
World War, 1939-1945--Refugees.
World War, 1939-1945--Search and rescue operations--Baltic Sea.
Princeton subject headings:
Baltic Sea--History.
World War, 1939-1945--Refugees.
World War, 1939-1945--Search and rescue operations--Baltic Sea.