Columbia subject headings:
Aqueducts--France--Congresses.
Aqueducts--Spain--Congresses.
Hydraulic structures--France--Congresses.
Hydraulic structures--Spain--Congresses.
Water-supply engineering--France--History--Congresses.
Water-supply engineering--Spain--History--Congresses.
Harvard subject headings:
Aqueducts--France--History--Congresses.
Aqueducts--Spain--History--Congresses.
France--Antiquities, Roman.
Romans--France--Congresses
Romans--Spain--Congresses
Spain--Antiquities, Roman.
Water-supply engineering--France--History--Congresses.
Water-supply engineering--Spain--History--Congresses.
Princeton subject headings: