Columbia subject headings:
English drama--20th century--History and criticism.
English drama--Irish authors--History and criticism.
Ireland--In literature.
Politics in literature.
Harvard subject headings:
English drama--20th century--History and criticism
English drama--Irish authors--History and criticism
Ireland--In literature.
Irish unification question in literature.
Political plays, English--History and criticism.
Politics in literature.
Princeton subject headings:
English drama--20th century--History and criticism.
English drama--Irish authors--History and criticism.
Ireland--In literature.
Politics in literature.