Columbia subject headings:
Harvard subject headings:
Communication--Economic aspects--Europe--History.
Communication--Economic aspects--Great Britain--History.
Communication--Europe--History.
Communication--Great Britain--History.
Postal service--Europe--History.
Postal service--Great Britain--History
Postal service--History--Sources.
Princeton subject headings:
Communication--Economic aspects--Europe--History.
Communication--Economic aspects--Great Britian--History.
Communication--Europe--History.
Communication--Great Britain--History.
Postal service--Europe--History.
Postal service--Great Britain--History.
Postal service--History--Sources.