Columbia subject headings:
Fortification--Italy--Tuscany--History.
Military architecture--Italy--Tuscany--History.
Military engineers--Italy--Tuscany--History.
Harvard subject headings:
Architects--Italy--Tuscany.
Engineers--Italy--Tuscany.
Fortification--Italy--Tuscany.
Military architecture--Italy--Tuscany.
Princeton subject headings:
Architects--Italy--Tuscany.
Engineers--Italy--Tuscany.
Fortification--Italy--Tuscany.
Military architecture--Italy--Tuscany.