Columbia subject headings:
Harvard subject headings:
Alps Region--Relations--Congresses.
Communication and traffic--Alps Region--Congresses.
Local transit--Alps Region--History--Congresses.
Transit, International--Alps Region--History--Congresses.
Transportation--Alps Region--History--Congresses.
Princeton subject headings:
Alps Region--Relations--Congresses.
Communication and traffic--Alps Region--Congresses.
Local transit--Alps Region--History--Congresses.
Transit, International--Alps Region--History--Congresses.
Transportation--Alps Region--History--Congresses.