Columbia subject headings:
Altarpieces, Medieval--Italy--Siena.
Altarpieces--Italy--Siena.
Painting, Italian--Italy--Siena.
Harvard subject headings:
Altarpieces, Medieval--Italy--Siena.
Altarpieces--Italy--Siena.
Duomo di Siena.
Painting, Italian--Italy--Siena
Princeton subject headings:
Altarpieces, Gothic--Italy--Siena.
Altarpieces, Italian--Italy--Siena.
Duomo di Siena.
Painting, Gothic--Italy--Siena.
Painting, Italian--Italy--Siena.