Columbia subject headings:
Austrian drama--20th century--Congresses.
Theater--Austria--Congresses.
Theater--Austria--History--20th century--Congresses.
Harvard subject headings:
Austrian drama--20th century--History and criticism--Congresses.
Theater--Austria--History--20th century--Congresses.
Princeton subject headings:
Austrian drama--20th century--Congresses.
Theater--Austria--Congresses.
Theater--Austria--History--20th century--Congresses.