Columbia subject headings:
Harvard subject headings:
Envelopes (Stationery)--History.
Envelopes, Addressing of--History.
Letter services--Germany--Nuremberg--History.
Letter services--Italy--History.
Letter services--Switzerland--History.
Postal service--Germany--Nuremberg--History.
Postal service--Italy--History.
Postal service--Switzerland--History.
Princeton subject headings:
Postage stamps--Germany--History.