Columbia subject headings:
Harvard subject headings:
Postcards--Switzerland--History--20th century.
Prisoner-of-war camps--Switzerland--History--20th century.
Prisoners of war--Switzerland--History--20th century.
Refugees--Switzerland--Correspondence.
Soldiers--Switzerland--Biography.
Switzerland--History--20th century.
World War, 1939-1945--Concentration camps--Switzerland.
World War, 1939-1945--Evacuation of civilians--Switzerland.
World War, 1939-1945--Postal service.
World War, 1939-1945--Switzerland--Prisoners and prisons.
Princeton subject headings:
Postcards--Switzerland.
Prisoners of war--Switzerland.
World War, 1939-1945--Postal service.
World War, 1939-1945--Prisoners and prisons.