Columbia subject headings:
American poetry--20th century--History and criticism.
English poetry--20th century--History and criticism.
Poetry, Modern--20th century--History and criticism.
Harvard subject headings:
American poetry--20th century--History and criticism
English poetry--20th century--History and criticism
Essays.
Heaney, Seamus, 1939-2013--Literary collections.
Lectures
Literary criticism
Poetry, Modern--20th century--History and criticism
Princeton subject headings:
English poetry--20th century--History and criticism.