Columbia subject headings:
Syria--History--333 B.C.-634 A.D.
Tadmur (Syria)
Harvard subject headings:
Syria--Antiquities.
Syria--History--333 B.C.-634 A.D.
Tadmur (Syria)--History.
Princeton subject headings:
Rome--History--Period of military anarchy, 235-284.
Tadmur (Syria)--History.
Zenobia, Queen of Palmyra