Columbia subject headings:
Harvard subject headings:
Caves--Meuse River Valley.
Mesolithic period--Meuse River Valley.
Meuse River Valley--Antiquities, Roman.
Meuse River Valley--Antiquities.
Romans--Meuse River Valley.
Princeton subject headings:
Caves--Meuse River Valley.
Mesolithic period--Meuse River Valley.
Meuse River Valley--Antiquities, Roman.
Meuse River Valley--Antiquities.
Romans--Meuse River Valley.