Columbia subject headings:
Popper, Karl R. (Karl Raimund), 1902-1994--Congresses.
Harvard subject headings:
Popper, Karl R. (Karl Raimund), 1902-1994--Congresses.
Princeton subject headings:
Methodology--Congresses.
Popper, Karl Raimund, Sir, 1902---Congresses.
Science--Philosophy--Congresses.