Columbia subject headings:
Yeats, W. B. (William Butler), 1865-1939.
Harvard subject headings:
Courage in literature
Heroes in literature
Yeats, W. B. (William Butler), 1865-1939
Yeats, W. B. (William Butler), 1865-1939--Criticism and interpretation.
Princeton subject headings:
Yeats, W. B. (William Butler), 1865-1939.