Columbia subject headings:
Ferdinand I, Holy Roman Emperor, 1503-1564.
Reformation--Holy Roman Empire.
Harvard subject headings:
Austria--Kings and rulers--Biography.
Ferdinand I, Holy Roman Emperor, 1503-1564.
Holy Roman Empire--History--Ferdinand I, 1556-1564.
Holy Roman Empire--Kings and rulers--Biography.
Princeton subject headings:
Ferdinand I, Holy Roman Emperor, 1503-1564.
Holy Roman Empire--History--Ferdinand I, 1556-1564.