Columbia subject headings:
Pirandello, Luigi, 1867-1936--Criticism and interpretation.
Pirandello, Luigi, 1867-1936. Enrico IV.
Harvard subject headings:
Pirandello, Luigi, 1867-1936--Criticism and interpretation.
Pirandello, Luigi, 1867-1936. Enrico IV.
Princeton subject headings:
Pirandello, Luigi, 1867-1936--Criticism and interpretation.