Columbia subject headings:
Authors, Polish--20th century--Biography--Congresses.
Lem, Stanisław--Congresses.
Science fiction, Polish--20th century--History and criticism--Congresses.
Harvard subject headings:
Authors, Polish--20th century--Biography--Congresses.
Lem, Stanisław--Congresses.
Science fiction, Polish--20th century--History and criticism--Congresses.
Princeton subject headings:
Lem, Stanisław--Congresses.