Columbia subject headings:
Harvard subject headings:
Railroad tunnels--Austria--Semmering (Region)--History.
Railroads--Austria--Semmering (Region)--Design and construction--History.
Railroads--Austria--Semmering (Region)--History.
Semmeringbahn--History.
Princeton subject headings:
Mountain railroads.
Railroad tunnels--Alps.
Railroad tunnels--Austria--Semmering (Region)--History.
Railroads--Alps.
Railroads--Austria--Semmering (Region)--History.
Railroads--Austria--Semmering (Region)--Pictorial works.
Semmeringbahn.