Columbia subject headings:
Harvard subject headings:
Postal service--Germany--History--Periodicals.
Postal service--History--Periodicals.
Telecommunication--Germany--History--Periodicals.
Telecommunication--History--Periodicals.
Princeton subject headings:
Periodicals.
Postal service--Germany--History--Periodicals.
Postal service--History--Periodicals.
Telecommunication--Germany--History--Periodicals.
Telecommunication--History--Periodicals.