Columbia subject headings:
Transportation--France--Congresses.
Transportation--Germany--Congresses.
Harvard subject headings:
Choice of transportation--Congresses.
Transportation--France--Congresses.
Transportation--France--Passenger traffic--Congresses.
Transportation--Germany--Congresses.
Transportation--Germany--Passenger traffic--Congresses.
Princeton subject headings:
Choice of transportation--Congresses.
Transportation--France--Passenger traffic--Congresses.
Transportation--Germany--Passenger traffic--Congresses.